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Aggression and Violent Behavior 19 (2014) 1–11

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Aggression and Violent Behavior

Serial killers: I. Subtypes, patterns, and motives

Laurence Miller ⁎ Royal Palm Medical Centre 1599 NW 9th Ave., Ste. 206 Boca Raton, FL 33486 United States

⁎ Tel.: +1 561 392 8881. E-mail address: [email protected].

1359-1789/$ – see front matter © 2013 Elsevier Ltd. All ri http://dx.doi.org/10.1016/j.avb.2013.11.002

a b s t r a c t

a r t i c l e i n f o

Article history: Received 8 July 2013 Received in revised form 5 October 2013 Accepted 8 October 2013 Available online 14 November 2013

Keywords: Criminal profiling Forensic psychology Mass homicide Serial homicide Serial killers

Part I of this two-part article outlines the history of serial killing and describes the varying patterns and motives for this type of crime. It reviews the assorted typologies of serial killers that have been elaborated by different researchers and offers an integrative classification of primary serial killer subtypes. In addition to the commonly cited male, heterosexual, solitary sadistic sexual homicide offender, this article describes a number of subpopu- lations of serial killers, including sadist–masochist, female, couple, homosexual, and professional serial killers. Part II will examine the developmental factors, neuropsychodynamics, and forensic applications of serial killing.

© 2013 Elsevier Ltd. All rights reserved.

Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2. History and concept of serial killing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 3. Definition and description of serial killing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Characteristics of serial killers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

4.1. Demographic and descriptive features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4.2. Criminal history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4.3. Characteristics of the crime . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

5. Typologies of serial killers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 5.1. Deitz typology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 5.2. Holmes typology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 5.3. Rappaport typology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5.4. Sewall and colleagues typology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

5.4.1. Competitively disadvantaged offenders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5.4.2. Psychopathic offenders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5.4.3. Sadistic offender . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

5.5. Serial killer typologies: conceptual commonalities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5.6. Organized–disorganized dichotomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

5.6.1. Organized serial killer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5.6.2. Disorganized serial killer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

6. Special populations of serial killers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 6.1. Sadist–masochist serial killers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 6.2. Female serial killers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 6.3. Couple serial killers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 6.4. Solo versus couple-based female serial killers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

6.4.1. Solo, purpose-oriented serial homicide offenders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 6.4.2. Partnered, pleasure-oriented serial homicide offenders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

6.5. Homosexual serial killers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 6.6. Homosexual serial killer typologies: conceptual commonalities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

ghts reserved.

2 L. Miller / Aggression and Violent Behavior 19 (2014) 1–11

6.7. Professional serial killers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 7. Summary and conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

1. Introduction

Question: how is a great white shark like a serial killer? According to a study by Martin et al. (2009) in the Journal of Zoology, except for the water, it might be hard to tell them apart. In an interesting twist on ethological research, marine biologists teamed up with a criminal profil- er and applied the investigative methodology of geographic profiling to the study of shark predation. The researchers found that the sharks do not attack their prey at random, but stalk specific victims, lurking out of sight. The sharks hang back and observe from a not-too-close, not-too-far base, and hunt strategically. They prefer prey animals that are young and alone, then typically strike from below, and try to attack when no competing sharks are in their territory. Older sharks are stealthier and more successful than younger sharks, indicating that these oceanic predators, like their human counterparts, learn from experience and improve their hunting technique over time.

In the United States, homicide accounts for approximately 20,000 deaths annually (Flowers, 2002). In ordinary civilian life, most people do not kill, but we may enjoy watching others do it on television and at the movies, or by reading about it in books or on websites. Scholars busy themselves studying murder and other crimes, which is a way of intellectually objectifying and emotionally detoxifying these uncom- fortable subjects. Perhaps some of us have secret fantasies that resemble those of the murderer; yet, we retain control of our actual behavior and remain law-abiding members of society. For serial killers, however, such fantasies outgrow their vicarious function and become a cognitive staging ground for the actual commission of their crimes (Hickey, 1997; Simon, 1996).

The serial killer watches the same spy movies and police shows we do, cultural narratives where street detectives or glamorous interna- tional agents doggedly and cleverly pursue malfeasors (the lead charac- ter of one such popular 1980s TV detective series was actually named “Hunter”), for the greater good of society. At the same time, the nascent killer also absorbs society's fascination with media portrayals of the con- scienceless power of rogues and outlaws who “don't play by the rules,” and he feels the same tingle of exhilaration at the opportunity to vicar- iously track down and destroy those who “have it coming.”

However, whereas our involvement in such mayhem begins and ends at the level of fantasy, the perpetrator of serial killing, or serial murder, or serial homicide (the most common terms) goes further. For the serial killer, such fantasies are not cathartic, but facilitative, the first step, not the last. His fantasies build, along with a neuropsycho- dynamically driven hunger that only the orgiastic release of torturing and murdering another human being will provide. What for most people (typically men) may constitute a momentary journey into cruelty during the “heat of battle,” as, for example, in military service, becomes for the serial killer his life's guiding purpose and mission. That is why he is so relentless. That is why he will always continue to kill until he is dead or securely confined.

2. History and concept of serial killing

Ancient Roman emperors, such as Caligula, indulged their sadistic inclinations at will, as no doubt did many a despot with a cruel streak, who could exert state-sanctioned power over other people. In the 1400s, the French nobleman Gilles de Rais raped, tortured, and killed several hundred children, reportedly deriving more pleasure from their agonies – which included dismemberment, neck-breaking, and decapitation – than from the act of sex with them (Benedetti, 1972).

In 16th-century Europe, the brutal mutilations inflicted on some serial homicide victims led to the deaths being blamed on werewolves, since only a supernaturally and bestially malevolent being could possibly be responsible for killings of such savagery (Schlesinger, 2000).

In 1866, Richard von Krafft-Ebing published his classic text, Psychopathia Sexualis, which contained the first comprehensive tract on serial sexual homicide in the modern era, presenting a care- ful description of many of the characteristics that serial homicide in- vestigators still use today to profile crimes. These include the tendency to lie and manipulate, take souvenirs from the crime scene, use ligatures, prolong torture for increased sexual arousal and pleasure, engage in an escalation of sadistic behavior, use por- nography, humiliate and degrade victims, and carefully plan the murders to avoid detection. von Krafft-Ebing also noted that these offenders often displayed no obvious signs of major psychopatholo- gy. Finally, he described signature aspects of the crime, which repre- sent the killer's idiosyncratic touches on the crime scene believed to reflect his personality and psychopathology, and which is often used as a key datum in modern criminal profiling (Geberth, 1996; Hicks & Sales, 2006; Palermo & Kocsis, 2005).

Probably the most famous serial murderer of all time, Jack the Rip- per, terrorized Victorian England in the late 1800s (Begg, Fido, & Skinner, 1991). Like many modern serial killers, Jack specialized in mur- dering prostitutes, stabbing, disemboweling, sexually mutilating the victims and, in some cases, carefully removing their internal organs and arranging them around the victim or taking them from the crime scene. The surgical precision with which these eviscerations were per- formed led to speculation that the Ripper may have been a practicing surgeon at one of the local hospitals in the Whitechapel district of London; such a “double life” is not uncommon in the histories of many serial killers today. A further similarity to some modern cases was Jack's proclivity for sending taunting letters to the press, threaten- ing to continue and escalate his crimes. As with many modern unclosed files, the Ripper case remains unsolved to this day: Jack's killing spree apparently ended as abruptly as it began and his identity was never discovered.

Resembling more a milquetoast than a monster, Albert Fish was a bow-tied sadist, masochist, pedophile, serial murderer, and cannibal who operated from the 1920s to the 1930s in New York (Schechter, 1990). In one instance, he abducted a schoolgirl under the guise of tak- ing her to a birthday party, strangled her, cut up her body, made a stew of her remains (complete with potatoes and vegetables), and consumed this dish over the next several days. As a final sadistic touch, six years after the murder, Fish sent a letter to the child's mother, detailing how he had killed and eaten her daughter. This led to his arrest shortly after the letter was traced to his home. In addition to serial murder, Fish engaged in a variety of sadomasochistic behaviors, including eating his own excrement, inserting rose stems in his penis, and inserting 29 sewing needles into his groin, clearly visible on X-ray years later. As discussed further below, the Albert Fish case illustrates the heterogene- ity and versatility of sadomasochistic behaviors displayed by serial killers that appear to involve the common intertwined phylogenetic themes of sex, death, and eating.

One of the more famous serial killers of modern times was Albert DeSalvo, commonly known as the Boston Strangler, who killed 13 women over an 18-month period in the early 1960s (Rae, 1967). DeSalvo displayed the kind of escalation in violence often seen in serial homicide careers, first as a voyeur, then progressing to burglary, later becoming a rapist, and finally a serial murderer. Also typical of many

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serial killers was his penchant for using charming seduction to gain entry to his victims' homes, often posing as a repairman or a scout for a modeling agency. The victims were strangled and stabbed, and broomsticks and other objects were inserted into their bodies. His sig- nature behavior often consisted of placing a bow made from the victims' stockings around their necks.

The term serial murderer was coined by FBI Special Agent Robert Ressler during the “Son of Sam” killings (which were actually shootings of young women, not sexual homicides per se) in New York City in the 1970s. Up to that time, there were probably less than 10 serial mur- derers identified in the United States. By the 1980s, the FBI calculated that approximately 35 serial killers were active in the U.S., and in recent years that estimate has swelled to between 200 and 500, accounting for 2000 to 3500 murders a year, more than 10% of all murders in the U.S. In fact, with only 5% of the world's population, some authorities believe that the U.S. may have up to 75% of the world's serial killers, perhaps due to the open, mobile nature of American society. The increase in the number of serial killers captured and recorded may be due an actual surge in the rate of this crime or to better profiling and crime-solving techniques. However, despite the singular successes glorified in the popular media, the case clearance rate (proportion of crimes that are solved) of serial murders is fairly low. Thus, serial killers are precisely so dangerous and frightening because they rarely stop killing unless they die or are apprehended (Bureau of Justice Statistics, 2003; Chan & Heide, 2009; Flowers, 2002; Hickey, 1997, 2003; Holmes, 1989; Holmes & Holmes, 1994, 1996; Johnson & Becker, 1997; Miller, 2000; Palermo & Kocsis, 2005; Simon, 1996; Volavka, 1999).

Since the late 1970s, the media and the public have become increas- ingly fascinated by serial killers (Table 1). However, because human na- ture and behavior are relatively stable across time and place, virtually all of the contemporary offenders chronicled in modern clinical case histo- ries and media narratives could find familiar chapters within the pages of Krafft-Ebing's 1866 treatise. For example, prostitutes continue to be a favored target of serial killers, either because of psychodynamic preoc- cupation with the sins of tainted womanhood, or because they are con- veniently disenfranchised victims (Miller, 2008b; Miller & Schlesinger, 2000; Spungen, 1998) who are easy to find, isolate, and kill without arousing too much of a public outcry—as opposed, for example, to preppie college students or young urban professionals.

Also recently seen are cases of vampirism and cannibalism: Jeffrey Dahmer could trade recipes with Albert Fish on their mutual taste for

Table 1 Some famous American serial killers.

Albert Fish: Active 1928–1935. Kidnapped, tortured, mutilated, and ate children. For at least som and ate human feces. In one case, he sent a detailed letter to a murdered little girl's parents,

Henry Lee Lucas: Active 1960–1983. Initially boasting of mutilating and killing up to 500 peo Albert DeSalvo: Active 1962–1964. The “Boston Strangler” sexually assaulted and strangled wo in the 1969 Rolling Stones' song, Midnight Rambler.

John Wayne Gacy: Active 1972–1978. Posed as a police officer, detained boys and young men house.

Arthur Shawcross: Active 1972–1990. Strangled or beat to death young women, mainly pros Ted Bundy: Active 1974–1982. Charming and seductive, he raped, killed, and mutilated his f Unsuccessfully tried to feign multiple personality disorder as an insanity defense.

David Berkowitz: Active 1976–1977. Terrorized the New York City area as the “Son of Sam,” from his neighbor's dog. Stalked young, brunette, long-haired women and shot them to de

Dennis Rader: Active 1976–1986. Called himself the “BTK Killer” for “Bind-Torture-Kill.” Tortur 18 years, then re-emerged, with new media messages, which led to his arrest.

Wayne Williams: Active 1979–1982. Convicted of murdering 21 African-American children in research has shown this not to be the case.

Jeffrey Dahmer: Active 1987–1991. Lured boys and young men to his apartment, drugged the body parts around his home. Also experimented with making “sex slave zombies” out of s

Aileen Wuornos: Active 1989–1991. A rare female serial killer, she shot seven men to death, cl her was titled, Monster, although it could be argued that her crimes were considerably less

John Allen Muhammad: Active 2002. Teaming up with a young protégé, Lee Boyd Malvo, thes 9–11 terrorist attacks. The duo killed a total of 10 people with a single hunting rifle from t might be wrought if a dozen or a hundred dedicated snipers were to coordinate such attac

anthrophagy, that is, eating of humans. Children also continue to be vic- timized: John Wayne Gacy would feel right at home in the 1400 s with Gille de Rais. Many contemporary offenders are highly intelligent and outwardly charming, yet often with histories of fire-setting and animal cruelty, and some still send taunting letters to the press. In the popular imagination, extraterrestrial aliens have now replaced werewolves as suspects in particularly gruesome livestock mutilations which may in reality represent training exercises for a few disturbed individuals who might later go on to carve up humans. And like their predecessors, many modern serial murderers have had seemingly stable relationships with girlfriends or wives, many of whom claim ignorance when their mate's double life is exposed or who, in some cases, may be complicit in the crimes (see below).

Indeed, so great is the public's fascination with the kind of con- scienceless power embodied by the serial killer, so great is the thrill that many people get from momentary vicarious identification with such pure remorselessness, that some serial killers – much like gangsters – have achieved the status of criminal rock stars, appearing in numerous crime anthologies, on T-shirts, in song lyrics, and especially in movies and on TV (Table 1). For example, Ed Gein wore the skin of his victims during his autoerotic transvestite rituals: this became the inspi- ration for the “Buffalo Bill” character in Silence of the Lambs (LaBrode, 2007).

But at the same time that we are enthralled by the serial killer, we are also afraid of him. Surveys have shown that the public puts their fear of serial killers second only to the fear of terrorism (Schlesinger, 2000). Again, this reflects the fact that one's idiosyncratic notions of “good” and “bad” human behavior are often determined by individual personalities, circumstances, ideology, and culture (Miller, 1990, 2012). Vegetarians think meat-eaters are barbarians. Steak-lovers chomp on their juicy morsels with gusto, but would retch at the thought of eating the flesh of another human being. Fore Islanders of New Guinea eat the brains of their recently deceased relatives as a religious ritual and would regard as profoundly disrespectful any family member who declined. The patriarchs of the Old Testament routinely practiced animal sacrifice as a devotion to God, but regarded as an abomination the human child sacrifice practiced by contemporaneous worshippers of Baal. Eating one's enemy to assimilate his strength and power, or the taking of body parts as trophies, has characterized victorious war- riors in every age; as recently as September, 2010, U.S. Army soldiers were charged with keeping leg bones, finger bones, and teeth from

e of his crimes, he claimed he was ordered by God to carry them out. Also self-mutilated describing in sadistic detail what he did to the child; this, fortunately, led to his capture. ple, he later recanted many of these claims and was convicted of murdering 11 victims. men from 19 of 85 years of age. Once of the first “celebrity serial killers,” he was lyricized

at his home, sexually assaulted them, strangled them, and buried their bodies under his

titutes, and dumped their bodies along a river in upstate New York. emale victims, displaying trophies, including severed heads, in his apartment.

based on his letters to the press claiming to receive demonic messages and commands ath with a handgun, leading to another moniker, the “44-Caliber Killer.” ed and murdered his victims and sent letters and packages to the media. Disappeared for

the Atlanta area. At the time, black serial killers were thought to be a rarity; subsequent

m, sexually assaulted, murdered, mutilated, and cannibalized them, and stored multiple ome of his victims by performing crude lobotomies on their brains. aiming they had tried to rape her while she was working as a prostitute. The movie about monstrous than those of many of the male serial killers described here. e “Beltway Snipers” paralyzed the Washington DC area, which was still reeling from the he trunk of an old car, leading pundits to speculate nervously about what kind of havoc ks around the country.

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slain Afghanis. Thus, the study of serial killers – by whom we are simul- taneously fascinated and repelled – must be interpreted in the context of our own clinical and cultural environment.

3. Definition and description of serial killing

By the FBI's operational definition, serial murderers are those who, either alone or with an accomplice, kill at least three people over a peri- od of time, with “cooling-off” periods between the murders, indicating premeditation of each killing. When serial killers are identified, it is sometimes because, in acting out their fantasies, they leave their charac- teristic signatures on their victims' bodies or at the crime scene.

Serial murderers are distinguished from mass murderers, who kill multiple victims in a single incident, and whose fantasies tend to involve revenge against actual or imagined persecutors. Whereas the torture and murder activities of serial killers tend to be slow and close-up, involving low-tech weapons that gouge, flay, or strangle, the typical goal of mass murderers is to kill many as many victims as possi- ble, quickly, efficiently, and at once, using the highest level of lethal technology available to them to do the most damage — handguns, assault weapons, explosives, or arson (Dietz, 1986; Fox & Levin, 1994, 1998; Holmes & Holmes, 2001a, 2001b; Meloy, 1997; Miller, 1999, 2006a, 2006b, 2007, 2008a; Palermo, 1997; Simon, 1996).

4. Characteristics of serial killers

Although heterogeneity exists within any psychological or crimino- logical category (also see below), certain common features characterize serial killers.

4.1. Demographic and descriptive features

The typical serial murderer is a white male in his 20s to 40s, although older cases are seen, especially for killers who have escaped detection for many years. Minority groups are becoming increasingly represented. The individual is often a loner, although many are married or live in relatively stable relationships. He often appears to others as intelligent and charming. He may be stably housed and employed or he may change jobs and residential locales frequently (Chan & Heide, 2009; Fox & Levin, 2003; Hazelwood, Dietz, & Warren, 1992; Holmes & De Burger, 1985; Lester, 1995; Palermo & Kocsis, 2005; Rappaport, 1988).

4.2. Criminal history

Although many serial killers, when apprehended, are found to have no prior criminal record, other studies have found that more than half of serial killers and other multiple homicide offenders have a past criminal history, and a few have shown a lifelong, often escalating, pattern of antisocial and criminal behavior (DeLisi, 2001, 2003, 2005; DeLisi & Scherer, 2006; Farrington, 2000; Fox & Levin, 2003; Harbort & Mokros, 2001; Nagin & Farrington, 1992; Piquero et al., 2003).

A frequent association appears between serial homicide and two other crimes: burglary and rape (DeLisi & Scherer, 2006; Douglas & Olshaker, 1998; Hazelwood & Douglas, 1980; Prentky et al., 1989; Ressler, Burgess, & Douglas, 1983; Ressler, Burgess, Douglas, Hartman, & D'Agostino, 1986). While the reasons for this particular association are not settled, it seems evident that both of these crimes involve the willful violation of another person's intimate self, either their home or their physical body. Burglaries and rapes are, in essence, both invasions of another person who has been dehumanized, much as past and pres- ent armies of conquest have engaged in rape and pillage of a conquered enemy's home territory, and so-called moralistic street robbery is often used by urban gangs to demoralize rivals (Jacobs & Wright, 2008). It should not be surprising, therefore, that this pattern of behavior may frequently escalate to the ultimate violation of a person's body: murder.

4.3. Characteristics of the crime

The victims of serial murder are predominantly female, white, and young adults, although same-sex murders are not uncommon, and some serial killers target children (see below). The majority of crimes are intraracial in nature, although a few serial killers have targeted ethnic groups different from themselves. As a notable exception to the general rule that we are most likely to be killed by someone we know, serial sexual homicides are twice as likely as other homicides to involve strangers (Flowers, 2001; Schlesinger, 2004, 2007).

Many serial killers collect trophies from the crime scene that they keep as mementos of the kill. These can range from articles of jewelry or clothing to internal organs or other body parts. Other serial killers engage in necrophilia, having sex with the dead body, some even pre- serving the body, or parts of it, for later use, or returning to the hidden crime scene to have repeated sexual contact with the decomposing corpse (LaBrode, 2007; Schlesinger, 2000; Schlesinger & Miller, 2003; Stein, Schlesinger, & Pinizzotto, 2010).

A significant number of serial killers engage in some form of post- mortem manipulation, mutilation, and/or cannibalism of their victims, some drinking the blood or eating parts of their victims at the crime scene or later, a practice called anthropophagy. Albert Fish made stew from at least one of his victims. Jeffrey Dahmer cannibalized several of his victims, storing the remains in his freezer like cuts of meat from the deli. He described the experience of eating his victims as sexually exhilarating (Ressler & Schactman, 1997).

In Reinfield's syndrome, also known as clinical vampirism, the killer feels a compulsion to drink the victim's blood. A number of researchers have commented on the similarity of these behaviors to the activities of predatory animals, including the common house cat, as well as to the customs of some preindustrial human societies, where drinking the blood or eating a body part (e.g., the heart) of a slain adversary is believed to convey the dead foe's power to the victor and to protect the warrior from vengeance by the victim's spirit. Examples include Maori warriors who taste the blood of their slaughtered enemies and executioners in Niger who lick the blood of their victims from the knife (Reiwald, 1950). In the contemporary movie and TV series, Highlander, a fictional secret race of immortals battle one another for supremacy, assuming their adversaries' knowledge and power by decapitating them.

Indeed, this fusion of killing, dismemberment, sex, and eating high- lights the primal interaction of these life and death forces in the survivalistic world that ancestral humans evolved in. In this sense, the serial killer frightens us all the more because his behavior strips away the veneer of civilized behavior and starkly illustrates the dark places our human natures can go (Miller, 1990, 2000, 2012).

As noted earlier, when serial killers are identified, it is often because, in acting out their fantasies, they leave their characteristic signature on the victims' bodies or at the crime scene. These are unique traces of behavior, thought to be idiosyncratic for that particular offender, that are often used as clues in profiling serial crimes. These may include pat- terns of attack, forms of bondage and torture, such as piquerism (intense, focused injury to the breasts of the victim), type of killing, postmortem body positioning, dress or undress, postmortem mutilation or dismem- berment (necrosadism), and trophy-taking.

Recent evidence suggests that such signatures do not necessarily re- main uniform for any single serial killer and that patterns of attack and crime scene characteristics can change over time (Schlesinger, Kassen, Mesa, & Pinozzotto, 2010). However, most authorities agree that serial sexual murderers act out an intense fantasy relationship with their victims, and thereby require the victims to be essentially anonymous props on whom they can inflict torment and death to achieve the exhilaration of sexual gratification. In this conceptualization, the selec- tion, stalking, and capturing of their victims are essentially their version of foreplay, with the torture and killing culminating in the orgasmic climax (Arrigo & Purcell, 2001; Chan & Heide, 2009; Geberth & Turco,

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1997; Hickey, 2003; Holmes & Holmes, 2001a, 2001b; Johnson & Becker, 1997; LaBrode, 2007; Langevin, 2003; Malmquist, 1996; Purcell & Arrigo, 2006; Schlesinger et al., 2010; Simon, 1996; Starr et al., 1984).

Some of the characteristic behaviors of serial killers may involve one or more paraphilias, such as fetishism (sexual preoccupation with body parts, inanimate objects, or bizarre activities); transvestism (dressing in the opposite sex's clothing); exhibitionism (public sexual displays), and voyeurism (surreptitious watching of others' sexual activity) (Arrigo & Purcell, 2001; Kerr, Beech, & Murphy, 2013; Myers, Husted, Safarik, & O'Toole, 2006).

One common fetish is the tendency for many serial killers to blind- fold their victims (Holmes, 1989). This probably has little to do with fear of identification, since the perpetrator intends to kill his victim eventually. More commonly, the motive involves injecting additional terror into the victim who cannot see what is happening to her, as well as effecting a further dehumanization of the victim by avoiding her gaze; for similar reasons, enucleation (gouging out of the eyes) is a common signature practice of serial killers, premortem or postmortem. Some authorities (e.g., Malmquist, 1996) also believe that blotting out the victim's eye contact is a means of counteracting the shame that may occasionally threaten to break through the serial killer's defenses, although the general consensus seems to be that most of these perpetrations have far too little conscience for shame to be a significant factor.

The serial killer devotes a tremendous amount energy and intelli- gence to the planning and execution of his attacks, becoming more pro- ficient each time he kills. Many serial killers are fascinated by police and detective work, and educate themselves in police procedures by reading books, taking courses, watching detective shows, doing online research, and speaking with local law enforcement officials. Some serial killers have impersonated police officers, and in some cases, have even inserted themselves into the investigations of the very crimes they have committed. John Wayne Gacy kept a police radio in his home; Wayne Williams photographed crime scenes; Ted Bundy once worked for the King County Crime Commission; Dennis Nilssen served a year on the London Police Force; and Edmund Kemper hung out at a bar near police headquarters, pestering off-duty officers with questions about the very murders he had committed (Simon, 1996; Starr, 1984).

5. Typologies of serial killers

Considering the amount of clinical and criminological attention that has been devoted to serial killers, it should not be surprising that a plethora of typologies has been developed to classify different types of perpetrators. The more well-known typologies are described below to illustrate the commonalities in observations among different re- searchers studying the same phenomenon.

5.1. Deitz typology

Dietz (1986, 1987) has proposed a typology that divides multiple murderers into five categories:

Psychopathic sexual sadists kill for the sheer pleasure of torturing and murdering their victims in a sexual way. This has also been termed lust murder or erotophonophilia (Hickey, 2003; Schlesinger, 2004). This is probably closest to the classic serial sexual homicide perpe- trator that is the subject of most descriptions. Examples include Ted Bundy and John Wayne Gacy. Crime spree killers embark on one or more jaunts of murder, usually in association with other crimes, most commonly robbery, but they also derive a thrill from the power and opportunity to flaunt author- ity that their acts entail. An historical example would be Bonnie and Clyde. A fictionalized cinematic portrayal appears in the 1994 film, Natural Born Killers.

Organized crime functionaries consist of professional or semiprofes- sional “hit men,” individuals who kill primarily for money, although they almost certainly enjoy a sense of power and control from being in this line of work. Other examples would include political assassins and territorial dispute killings by rival criminal gangs (Schlesinger & Miller, 2003). Custodial killers murder vulnerable victims who are supposed to be in their care. The most common examples include “angel of death” cases involving nurses in hospitals or nursing homes who surrepti- tiously murder ill or elderly patients, usually by asphyxiation or medication overdose. This group is likely to contain the highest number of female serial killers. An historical example is “Jolly” Jane Toppan, a nurse who, from 1895 to 1901, killed at least 31 hospital patients in Massachusetts (Raine, 2013). Psychotic killers murder under the influence of some form of delu- sion, such as defending themselves against malevolent pursuers (persecutory delusion) or receiving a divine command to rid the world of certain types of people (grandiose delusion).

5.2. Holmes typology

Another widely-used typology of serial killers (Holmes & De Burger, 1985, 1988; Holmes & Holmes, 1996) uses the following descriptors:

Spatial mobility killer. This typology maintains a clinical and forensic distinction between geographically stable serial murderers who live in one area and kill in that same or a nearby area, and geographically transient murderers who travel to other locales to commit their crimes. Visionary serial killer. This type of killer is induced to murder by delu- sions and/or command hallucinations which impel him to act. His victims are typically strangers, and his psychotic state at the time of his crimes sometimes results in the invocation of an insanity defense. This type appears closest to one variety of Dietz's (1986, 1987) psychotic killer, discussed above. Mission serial killer. This may represent another type of Dietz's psychotic killer, who is following a religious or political imperative to eradicate a certain group of people. In the Holmes classification, the mission killer need not be grossly psychotic, but simply affected by what would be described as a delusional disorder in DSM-5 (APA, 2013), or he may have no diagnosable mental disorder at all and may simply be acting on an extreme ideological belief that it is necessary to eliminate some identifiable class of “bad” people. Comfort-oriented serial killer. This killer's motive for murder contains at least some utilitarian purpose. It may include the hired assassin who kills purely for profit or the individual who murders family members for financial gain, in which case the profit motive may be admixed with feelings of hatred and revenge. Hedonistic serial killer. This is the type of serial murderer who derives sexual pleasure from the act of killing, which is usually prolonged and contains acts of mutilation, torture, dismemberment, and/or necrophilia. This is probably closest to Dietz's psychopathic sexual sadist, as well as to the classic description of the serial sexual homi- cide perpetrator. Power/control serial killer. Similar to the above type, this murderer derives pleasure from the prolonged torture and killing of another human being, but here the emphasis is more on the control and domination aspects of the killing than the sexual component per se. Of course, there is likely to be a great deal of overlap between these two categories.

A empirical study of the Holmes serial murderer typology was carried out by Canter and Wentink (2004), based on an analysis of crime scene evidence from 100 U.S. serial murders. They found limited support for aspects of the lust, thrill, and mission serial killer categories, and features of the power/control serial killer were found to generalize to serial killers as a whole, rather than forming a distinct type. The

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findings suggested that more attention should be paid to styles of inter- actions with victims, such as use of restraints, torture, mutilation and theft of property, rather than just inferring the motivations of individual offenders.

5.3. Rappaport typology

Rappaport's (1988) typology describes five types of serial killers:

Spree killers kill a series of victims during a continuous span of mur- der and are basically similar to Dietz's and others' descriptions of the crime spree killer. Functionaries of organized criminality are the contact killers, assas- sins, and hit men familiar from previous descriptions. Custodial killers are medical personnel, foster parents of disabled children, or other caretakers who poison or asphyxiate victims for financial gain, revenge, ideology, or twisted altruism (“angels of mercy/angels of death”). Psychotic killers murder under the influence of delusions and/or hallucinations, familiar from above descriptions. Sexually sadistic killers are murderers who derive sexual pleasure through inflicting pain on their victims, which describes both Dietz's psychopathic sexual sadist and Holmes' hedonistic serial killer.

5.4. Sewall and colleagues typology

Recently, Sewall, Krupp, and Lalumiere (2013) have pointed out that the crimes of sexual homicide perpetrators frequently occur in the context of a long and varied criminal history, involving an assort- ment of petty and violent crimes. Incorporating this data, these authors propose a serial killer typology containing the following three offender subtypes.

5.4.1. Competitively disadvantaged offenders These are life-long offenders whose criminal careers begin early,

often in childhood or adolescence, and involve numerous and sundry crimes, ranging from petty theft to sexual assault and murder. They frequently are developmentally and cognitively impaired, socially dis- advantaged, and lead a marginalized, criminal lifestyle. They would probably correspond to the definition of antisocial personality disorder described in DSM-IV-TR and DSM-5 (APA, 2000, 2013). When it occurs, sexual homicide is characterized by an impulsive, angry sexual attack, often in response to sexual rejection, and may begin as an attempted sexual assault that then escalates to murder.

5.4.2. Psychopathic offenders These offenders also begin their variegated criminal careers early,

but they are more neurodevelopmentally intact and able to maintain relatively stable lifestyles coexisting with their criminality. Cold and re- morseless, their crimes are likely to involve far more cunning and con- ning than the previous type, and they would probably correspond to the classic psychopath in criminological literature (Cleckley, 1941; Hare, 1993, 2006). Their primary motivation is the quest for thrills and excitement, which they obtain by manipulating, exploiting, and domi- nating other people. At times, this may include various forms of sexually sadistic behavior, but deliberate murder is likely to be the exception and, again, may occur in response to sexual rejection or in the course of a sadistic sexual act that gets out of hand.

5.4.3. Sadistic offender For this perpetrator, preoccupation with sexual torture and murder

has become a lifestyle, at first nurtured by fantasies and pornography, later perhaps practiced on animals, and finally expressed in acts against human beings. Intriguingly, this individual may have little or no crimi- nal history beyond his sexual homicides, and he is also likely to possess

the controlled predation characteristics of the psychopath, here focused exclusively and intently on his pursuit of gratification through sexual domination, torture, and murder.

5.5. Serial killer typologies: conceptual commonalities

The commonalities of typological descriptions coming from different observers in different times and places attests to a certain construct validity of the categories described by each. These appear to boil down to a basic set of common serial or multiple murderer subtypes:

Sexual sadists who kill for the intense pleasure derived from the domination, control, torture, humiliation, and murder of another human being. Delusional killers who are on a mission, either frankly psychotic or more ideologically-driven, to rid the world of persons they consider undesirable. Custodial killers who murder helpless or dependent persons under their care. Note that this group may overlap with the above, e.g. the health care worker who believes that society should not waste resources on sick or disabled people or that God has commanded that it would be more merciful to put them out of their misery. Utilitarian killers whose motive at least partly involves some practical financial or other material gain, although the motive may be mixed with anger or revenge, as in the aggrieved spouse who wants to put a final end to the wrangling over a bitter divorce.

5.6. Organized–disorganized dichotomy

Probably, the best-known, and increasingly controversial, classifica- tion scheme of serial killers is the one developed by the FBI's Behavioral Science Unit (BSU), which divides serial killers into organized vs. disor- ganized subtypes (Geberth, 1990; Geberth & Turco, 1997; Hazelwood & Douglas, 1980; Hickey, 1997; Palermo & Kocsis, 2005; Ressler, Burgess, & Douglas, 1988; Ressler et al., 1986).

5.6.1. Organized serial killer This perpetrator is above average in intelligence and considers him-

self superior to other people. He is meticulous in most aspects of his life and takes great care with personal appearance, grooming, and belong- ings. His crime is well thought out and carefully planned. The crime is usually committed away from his area of residence or work and he is quite mobile, often traveling long distances to commit his crimes. Fanta- sy and ritual are important to the organized killer, and he typically selects a stranger whom he considers the “right” type of victim in terms of age, physical appearance, behavior, and other qualities. The killer often carries a carefully prepared “torture kit” containing his pre- ferred implements of bondage and mutilation. He may follow and stalk this victim for hours or days, and he may take great pride in verbally manipulating his target into a position of vulnerability. His capture and control of the victim are calculated to afford him maximum power over his hapless prey. Alcohol is often used during the murder. He often takes a souvenir or trophy from his victim that he may later use to relive the event or enhance his fantasies surrounding the killing.

The organized serial killer is often familiar with police procedures and takes great pride in thwarting investigations and taunting law enforcement officials by the careful placement or concealment of evi- dence. In some cases, he is currently or has formerly worked in some branch of law enforcement or security, or aspired to do so. He may be a “student” of previous or contemporaneous serial killers, reading up on their exploits and even corresponding with them in prison. He typically learns from each of his own crimes and becomes increasingly sophisticated in his predatory and elusive tactics. Although casual observers may describe some serial killers as solitary and strange in

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their daily behavior, just as commonly he may appear normal and a “regular guy” to coworkers, family, and neighbors.

5.6.2. Disorganized serial killer This killer is average or below average in intelligence. He is often a

loner and a recluse. He is typically an underachiever, feels sexually and interpersonally inadequate, has a poor self-image, and is considered “weird” or “creepy” by acquaintances. He typically engages in such sex- ual activities as voyeurism, exhibitionism, lingerie thefts, and fetish bur- glaries, and uses sadistic and fetishistic fantasy and pornography in autoerotic activities. He is less careful about planning, and his crime scenes typically display more haphazard behavior. The violent offense is more impulsive and spontaneous, and the victim is often a target of opportunity. The disorganized killer's crimes lack the manipulation and cunning of the organized killer, and typically consist of “blitz attacks” that are intended to silence the victim quickly through blunt force trauma, following which, death usually follows quickly. Some attacks may be characterized by overkill, with multiple stabs and blows. Postmortem activities with the corpse may include biting, ex- ploratory dissection, mutilation, insertion of foreign objects, or mastur- bation onto the body, and there may or may not be actual penile penetration of the body. As the name implies, the crime scene is sloppy and disorganized, with minimal effort to conceal the evidence. Trophies are less frequently taken, but there may be a secondary robbery of opportunity.

As with most classificatory systems, intermediate types are fre- quently found, and sometimes a crime scene has elements of both orga- nized and disorganized categories, in which case it is called mixed (Geberth, 1990; Geberth & Turco, 1997; Hickey, 1997; Ressler et al., 1986, 1988). And, as with most psychological and criminological de- scriptors that deal with the untidy realities of human nature, authorities are coming to agree that the organized–disorganized system should be thought of more as a continuum than as a rigid dichotomy, and that this information should be utilized as one set of data, along with the other information collected in the course of an investigation (Hicks & Sales, 2006; Palermo & Kocsis, 2005; Schlesinger et al., 2010).

6. Special populations of serial killers

As described earlier, most serial killers, especially perpetrators of serial sexual homicide, are heterosexual males; however, like any gen- eralization about human nature, there are exceptions, and this section will consider some atypical varieties of serial killers and multiple homi- cide offenders.

6.1. Sadist–masochist serial killers

For a subset of serial killers, sadism is suffused with masochism, and these individuals derive pleasure from both giving and receiving pain (Hill, Habermann, Berner, & Briken, 2006; Knoll, 2009; Myers et al., 2006, 2008), often engaging in acts of self-mutilation, genital self- torture, or autoerotic asphyxiation (choking oneself almost to the point of unconsciousness during masturbation) (Everitt, 1999; Newton, 1990). Theories to explain the origin of these sadist–masochist serial offenders include: (1) identification with an earlier parental figure who has been both an aggressor and a victim (Macgregor, 1991; Stein, 2004); (2) being raised by a sexually provocative and punitive mother (Fox & Levin, 1994; Meloy, 2000); (3) becoming a “substitute victim” to vicariously experience the victims' pain, so as to heighten the offender's enjoyment of inflicting further pain (“Wow — if this is what it feels like, she must really be suffering…”) (Knoll, 2009); and (4) the grandiose sadism theory, in which the serial offender assumes the very identity of the victim by such actions as wearing her clothes, using her scalp as a wig, or even donning her skin as a jacket or shawl in order to extend his control over the victim beyond her death (Knoll, 2009; Warren, Hazelwood, & Dietz, 1996).

6.2. Female serial killers

As with violent crimes generally, male serial killers far outnumber female serial killers; however, over the past two centuries, about 15 per- cent of multiple homicide offenders have been women (Hickey, 1997; Kelleher & Kelleher, 1998; Malmquist, 1996; Perri & Lictenwald, 2010). There are several features of female serial killers that distinguish them from their male counterparts (Arrigo & Shipley, 2001; Flowers, 2001, 2002, 2006; Flowers & Flowers, 2001; Gurian, 2011; Kelleher & Kelleher, 1998; Palermo & Kocsis, 2005; Seagrave, 1992; Vronsky, 2007).

Unlike most male offenders, who kill out of compulsive rage and/or predatory lust, the motives behind serial homicides committed by women tend more toward monetary gain or histrionic attention- seeking. One exception may have been Eileen Wournos, who appears to have targeted male victims for motives of revenge and control. Fe- male serial killers tend to start somewhat later than males, usually around age 30. With regard to methodology, males use more brute force, and are more likely to shoot, strangle, suffocate, stab, or bludgeon their victims, who are usually strangers. Female serial killers are more likely to use poison as a lethal tool and to kill people they know, including family members, spouses (“black widow” cases), or depen- dent persons under their care (“angel of death” cases). Female serial ho- micides rarely require the kind of behavioral profiling applied to more traditional male cases.

Holmes and Holmes (1994) have elaborated a typology of female serial killers that parallels their typology for men:

Visionary serial killers: women who murder in response to delusional beliefs and/or hallucinated voices or visions. These women often suffer from a severe psychotic illness or mood disorder. Comfort-oriented serial killers: women who murder for financial or material gain. These are the “black widows” who may be highly mo- bile and skilled at changing their identities to lure unsuspecting vic- tims in diverse locations over time, thereby racking up a string of wealthy (and soon to be deceased) husbands, before being apprehended. Power-seeking serial killers: females who kill for the thrill and power gained through having full control over life and death of the victim. These include the “angel of death” cases that occur in health care facilities, although the killer may also target disabled family mem- bers, in which case the motive may be intertwined with material gain. Hedonistic serial killers: women who kill for sexual gratification. Un- like for men, this is typically rare as a primary motive in female serial killers. However, many of these women may derive gratification through their association with a male serial killer (see below). Disciple serial killers: women who kill under the command of a charismatic leader. Also rare, this may occur in a religious cult, more commonly out of personal allegiance to a charismatic male. The women who participated in the Tate-LaBianca murders in 1969 were under the thrall of Charles Manson, who remains in prison for the crimes. One of his disciples, Leslie Van Houton, was recently denied parole for the 13th time (Yahoo Voices, 2013).

6.3. Couple serial killers

Isn't it romantic when two homicidal lovers find each other? Cine- matically dramatized in the 1994 film, Natural Born Killers, these couple killers, partner killers, team killers, or tandem killers, as they are variously called, commit their murders as a duo, one member typically baiting, befriending, or seducing the victim into a position of submission, with the other member then perpetrating or joining in the killing. The motives may range from pure robbery–murder for profit to prolonged torture–murder for sexual gratification, with various gradations in between (Flowers, 2002; Flowers & Flowers, 2001; Owen, 2004).

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Jenkins (1990) has described four types of partner or group serial killer:

Dominant–submissive pairs. In this group, one member, usually the male, is the dominant partner. The woman participates in the murders mostly to please the man and often to act as the bait to lure victims. She may or may not participate in the actual torture and murder of the victim, but may observe it. These women may later describe themselves as reluctantly willing participants, but more commonly claim that they were “brainwashed” by the man, especially when facing serious legal charges. Equally dominant teams. Here, both members of the couple derive satisfaction from the killings, and both members are willing partici- pants in the crime. The woman may participate in the capture and binding of the victim, more rarely in the torture and murder itself. She may enjoy witnessing the crime. The couple may subsequently use their recollections of the crime, aided by photographs, videos, and even objects or body part trophies, to enhance their sexual activity. Extended family or group. These may range from actual biological fam- ilies who collaborate in serial murders to cult-families, such as the original Charles Manson group in the 1960s, in which unrelated peo- ple come together to form a small commune or tribal group that par- ticipates in homicide, typically for reasons ranging from robbery, to sexual gratification, to loosely-articulated philosophical/ideological reasons, sometimes with all of these motives combined. Organized or ceremonial social groups. Here, the ideological or politi- cal aspect has become more crystallized and systematic. These are often quasi-religious cults who commit mass murder, as in the 1995 Aum Shinrykio sarin gas attack on the Tokyo subway; however, in some cases, individual victims may be targeted as well. Sexual motives are far less common in these groups.

Mention should also be made of couples in which the woman may not actually participate in the crimes, but may herself be subjected to physical and sexual torture by her mate, as part of a consensual sadomas- ochistic relationship (Knoll, 2009; Warren & Hazelwood, 2002). In some of these cases, the man has also been a violent sexual offender outside of the relationship, including committing serial sexual homicide. The woman may or may not have known about her mate's crimes, reminis- cences of which are sometimes overtly or surreptitiously used to enhance the sexual pleasure of the man or both partners during their own sexual activities.

6.4. Solo versus couple-based female serial killers

The research of Gurian (2011) has led to a classification of female se- rial homicide offenders into two groups, based upon whether their crimes occur predominantly solo or in collaboration with a male partner.

6.4.1. Solo, purpose-oriented serial homicide offenders These women act alone and typically have some utilitarian motive

for their murders, even though they may be driven by psychopatholog- ical forces. These may include: (1) medical murderers (custodial killers, “angels of death”); profit murderers (“black widows” who kill husbands or other family members for money); and infanticides (multiple mur- ders of babies or young children; this may overlap with the custodial killer category).

6.4.2. Partnered, pleasure-oriented serial homicide offenders These women operate as part of a male–female serial murder team,

and their motives are typically more for personal gratification or to accommodate their partner's pleasure, including: (1) sexual sadists (the woman directly obtains pleasure from sexually torturing and mur- dering the victim); spree murderers (these usually occur in connection with other crimes, such as robbery, e.g. Bonnie and Clyde in the

1930s); profit murderers (similar to solo profit murderers, but here with the help of a male collaborator); cult or religious murderers (the killings are evoked by a charismatic male figure, e.g. the Tate-Labianca murders by the Charles Manson cult in 1969); male serial murderer– female accomplice (the woman serves primarily to aid and abet the male partner's depredations, such as luring victims or disposing of remains).

6.5. Homosexual serial killers

Another minority group in the serial killer universe consists of men who kill men. To date, there have been two main typologies developed to characterize this subgroup.

Geberth (1996) has offered a six-fold typology of homosexual serial homicide:

Interpersonal violence-oriented disputes. These are essentially “lover's quarrels” between homosexual partners or ex-partners that escalate to violence and murder. Unless they occur in a repeated pattern, it is unlikely that these acts meet the definition of serial homicides, per se. Forced sodomy. Here the gratification occurs through the act of sexu- al domination; death in these cases is usually accidental from exces- sive force used to brutalize or restrain the victim, most often either blunt force trauma or asphyxiation. Again, unless repeated, whether this meets the definition of serial homicide is questionable. Lust murder. This homosexual serial killing pattern probably comes closest to its heterosexual correlate described more commonly in the literature. In these crimes, the act is carefully premeditated and reinforced by sadistic fantasies. A certain type of victim may be stalked and seduced or overpowered into submission. Death is sadistically prolonged by torture and genital mutilation, trophies may be taken, and there may be concealment or crime scene staging of the body. Power murder. This is similar to the above category (and the two may well overlap), except that here, the sexual motivation is thought to be secondary to the thrill of power and domination. The victims are likely to be chosen for their physical vulnerability or social mar- ginality, such as children, teens, homeless men, drug addicts, or prostitutes. Although torture may be a feature of these killings, mutilation and dismemberment are just as likely to occur postmor- tem to create “shock value” for whoever discovers the body. Anger, more than lust, appears to drive this kind of homosexual serial homicide. Robbery–homicide. Here, the offender cruises the gay scene, often posing as a prostitute, looking for vulnerable victims to rob. Either deliberately as part of the plan, or inadvertently, some of these robberies end in murder. Homophobic murder. Episodes of gay-bashing may escalate to mur- der, again, either deliberately or accidently. The offenders may be self-repudiating homosexuals or homophobic heterosexual males.

More recently, Beauregard and Proulx (2007) have presented a ty- pology of homosexual serial homicide consisting of three categories.

Avenger. These individuals can be found among the ranks of homo- sexual, heterosexual, or bisexual prostitutes, whose lifestyles often re- volve around drug and alcohol consumption. Many have criminal records, including property crimes and violence. Psychological, physical, and/or sexual abuse during childhood appear to form the core dynamic of this pattern. The victim is often an older man (parental figure?). When a particular sex act is requested by this partner, pickup, or prosti- tution patron, it purportedly triggers a traumatic memory and violence erupts, which may eventuate in murder. Psychodynamically the offend- er is violently avenging himself on the hapless sex partner for past griev- ances and abuses he's suffered at the hands of others. The murder scene is characterized by signs of intense rage, and death usually occurs by

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strangulation or by use of a weapon of opportunity (sharp utensil, heavy object, belt or cord).

Sexual predator. This is the homosexual lust murderer, motivated by sadistic sexual fantasies, and on the prowl for vulnerable victims, often children or adolescents, who may be homosexual or not. There is often a prior criminal history. The killing is premeditated, the victim is stalked and abducted, and acts of torture, sodomy, and mutilation are typically performed in the course of the sadistically prolonged murder. This type most closely resembles the classic heterosexual serial sexual homicide offender.

Nonsexual predator. This type of murderer is not motivated by anger or by sadistic sexual fantasies, and the homicide is usually accidental or impulsive, occurring in the course of a robbery which is the primary mo- tive for the encounter. Often, the offender chooses his victim at a gay cruising venue, gains access to the victim's residence under the guise of a sexual liaison, attempts to rob the place, and when confronted by the victim, feels compelled to overpower him, killing him in the process. The attempted robbery may also occur in an alleyway, car, or other se- cluded locale. Sex may occur prior to the crime to pacify the victim, but the motive for the encounter is not primarily sexual. The offender may act alone or with an accomplice, and alcohol or drugs are frequent- ly involved. The perpetrator usually has a varied criminal history with an emphasis on property crimes.

6.6. Homosexual serial killer typologies: conceptual commonalities

The commonalities between these typologies appear to involve the following basic subtypes, which may overlap:

Profit. The motives are primarily to rob the victim, and sex is used as a lure or for pacification. Sadistic sexual gratification. Like many heterosexual sadistic sexual homicide perpetrators, the homosexual serial killer derives intense pleasure from the torture and murder of another human being. Power. The sexual component is ancillary to the motive of power and domination. Homophobia. The killer destroys that which he is most afraid of or disturbed by in himself or others.

6.7. Professional serial killers

Some people make their living killing other people. Their crimes can be said to be “serial” in the sense that these assassinations and contract killings are repeated, in the same way as anyone's job activities are carried out on a regular basis; however, these acts may be far removed psychologically from the type of sexually sadistic serial killer usually associated with this term. Schlesinger and Miller (2003) have explored the characteristics and psychological dynamics of what they terms contract murderers, which are classified into three types:

Amateur. These actually comprise the majority of murderers for hire, largely because of their low cost and relatively easy availability with- in the criminal subculture. This subject frequently has a history of petty crimes and of addiction, psychopathology, and a marginal life- style. The most common scenario involves a small-time crook who is hired by either an associate or a stranger to eliminate a no-longer- wanted spouse, lover, or personal rival for purposes of jealousy, money, or revenge. Although initially motivated by cash, many of these minor-league hitmen eventually come to enjoy the thrill and power associated with taking another person's life. Semiprofessional. The semiprofessional contract murderer is more technically savvy and has had more on-the-job training than the amateur. His criminal history is more lengthy and has involved more serious crimes, and he may have served terms in prison. Semi- professionals are less likely to show major psychopathology, but frequently display traits of antisocial personality and have histories

of violence in their background. The semiprofessionals plan their contract murders with a higher level of sophistication and attention to detail than do amateurs. The typical target of a semiprofessional contract murderer is the hirer's business associate or rival criminal, but in some cases, the semiprofessional is hired to eliminate a spouse or other family member. Because he is more expensive than the amateur, the clientele of the semiprofessional tend to be fi- nancially comfortable individuals with something substantial to gain from the target's elimination. Professional. As the name implies, the professional contract killer takes his vocation seriously, actually studying and training himself in the art and science of killing. He often has prior military, law en- forcement, or security experience and carries his lethal skills over into his criminal trade. Most of these professional assassins are on retainer with organized crime cartels, although some freelance their services to various criminal and political organizations as need- ed, commanding stiff fees for a professional job which typically in- cludes the efficient elimination of the target and cleaning up of evidence that could tie the crime to either the assassin or the hirer. The target is usually a prominent functionary in a rival criminal orga- nization or a political figure. The job may also involve multiple tar- gets, in which case, bombing or arson may be involved, in which case it may overlap with terrorism (Miller, 2006a, 2006b). In some cases, certain government agencies may retain the professional's services when they want to carry out a military or political assassina- tion that cannot be traced back to them.

Serious psychopathology is uncommon in these individuals and, in- deed, the best of them must possess keen intelligence and the ability to think quickly and flexibly and to restrain impulsive action. While con- tract killers by definition could be said to harbor antisocial personality traits, many of these individuals rationalize their actions as being on a par with paramilitary mercenary soldiers and, as noted above, some of them may actually have had this experience. However, it is not unrea- sonable to speculate that some degree of narcissistic power thrill under- lies these assassins' motivation for continuing in this line of work.

7. Summary and conclusions

Part I of this two-part article illustrates that serial killers have been around for as long as people have lived in aggregated societies. Although the most common type of serial killer discussed by law enforcement and featured in the popular media is the sadistic serial sexual homicide of- fender, there is a wide range of serial killer subtypes, each with differing and overlapping motives. However, there appears to be a general con- sensus on the following basic categories: (1) sexual sadists who kill for the intense pleasure derived from the domination, control, torture, humiliation, and murder of another human being; (2) delusional killers who are on a psychotic or ideologically-driven mission to rid the world of “undesirable” persons; (3) custodial killers who are often health care professionals and who murder helpless or dependent persons in their charge; (4) utilitarian killers whose motive at least partly involves some practical financial or other material gain, although this motive may be mixed with anger or revenge. Finally, although most serial killers are single heterosexual males, research has documented the presence of female, homosexual, couple, and professional serial killers. Part II will examine the developmental factors, neuropsychodynamics, and forensic applications of serial killing.

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