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Criminalistics: An Introduction to Forensic Science

Chapter 1

Introduction

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Definition (1 of 2)

• In its broadest definition, forensic science is the

application of science to criminal and civil laws.

• The subject matter of this book emphasizes the

application of science to those criminal and civil laws that

are enforced by police agencies in a criminal justice

system.

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Figure 1–1: A Scene from CSI, a Forensic

Science Television Show

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Definition (2 of 2)

• Forensic science owes its origins to individuals such as

Orfila, Bertillon, Galton, Lattes, Goddard, Osborn, and

Locard, who developed the principles and techniques

needed to identify or compare physical evidence.

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History (1 of 5)

• Mathieu Orfila

– The father of forensic toxicology.

• Alphonse Bertillion

– Devised the first scientific system of personal

identification in 1879.

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Figure 1–3: Bertillon’s System of Bodily Measurements

as Used for the Identification of an Individual

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History (2 of 5)

• Francis Galton

– Conducted the first definitive study of fingerprints and

their classification.

• Leone Lattes

– Developed a procedure to determine blood type from

dried bloodstains.

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History (3 of 5)

• Calvin Goddard

– Refined the technique of determining if a particular

gun fired a bullet by using the comparison

microscope.

• Albert Osborn

– Developed the fundamental principles of document

examination.

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History (4 of 5)

• Walter McCrone

– Advanced the field of microscopy and its application to

examining evidence.

• Hans Gross

– Wrote the first treatise describing the application of

scientific principles to the field of criminal investigation.

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History (5 of 5)

• Edmond Locard

– Incorporared Gross’ principles within a workable

crime laboratory.

• Locard’s Exchange Principle

– States that when a person comes in contact with an

object or another person, a cross-transfer of materials

occurs.

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The Crime Lab (1 of 2)

• The ever increasing number of crime laboratories is partly

the result of the following:

– Supreme Court decisions in the 1960s responsible for

police placing greater emphasis on securing

scientifically evaluated evidence.

– Crime laboratories inundated with drug specimens

due to accelerated drug abuse.

– The advent of DNA profiling.

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The Crime Lab (2 of 2)

• At present, approximately 411 public crime laboratories

operate at various levels of government—federal, state,

county, and municipal.

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Crime Laboratory Units (1 of 6)

• The technical support provided by crime laboratories can

be assigned to five basic services:

– The physical science unit incorporates the

principles of chemistry, physics, and geology to

identify and compare physical evidence.

– This may include the analysis of drugs, glass, paint,

explosives, and soil.

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Crime Laboratory Units (2 of 6)

– The biology unit applies the knowledge of biological

sciences in order to investigate biological fluids or

touch samples for DNA, as well as compare hair and

fiber samples.

– The firearms unit investigates discharged bullets,

cartridge cases, shotgun shells, and ammunition. Tool

mark comparisons may also be made in this unit.

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Crime Laboratory Units (3 of 6)

– The document examination unit provides the skills

needed for handwriting analysis and other

questioned-document issues such as obliterations,

erasures, and burnt documents.

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Crime Laboratory Units (4 of 6)

– The photography unit applies specialized

photographic techniques for recording and examining

physical evidence.

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Crime Laboratory Units (5 of 6)

• Optional Services by Full-Service Labs

– The toxicology unit examines body fluids and

organs for the presence of drugs and poisons.

– The latent fingerprint unit processes and examines

evidence for latent fingerprints.

– The polygraph unit conducts polygraph tests.

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Crime Laboratory Units (6 of 6)

– The voiceprint analysis unit attempts to link a

recorded voice to a particular suspect.

– The crime-scene investigation unit dispatches

specially trained personnel to the crime scene to

collect and preserve physical evidence.

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Functions of a Forensic Scientist (1 of 3)

• A forensic scientist must be skilled in applying the

principles and techniques of the physical and natural

sciences to analyze the many types of evidence that may

be recovered during a criminal investigation.

• The analysis of physical evidence requires that the

techniques used first be tested using the scientific

method.

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Analyzing Physical Evidence Requires

Utilizing the Scientific Method

• Scientific Method

– Formulate a question worthy of investigation.

– Formulate a reasonable hypothesis to answer the

question.

– Test the hypothesis through experimentation.

– Upon validation of the hypothesis, it becomes suitable

as scientific evidence.

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Functions of a Forensic Scientist (2 of 3)

• A forensic scientist may also provide expert court

testimony.

• An expert witness is an individual whom the court

determines possesses knowledge relevant to the trial that

is not expected of the average person.

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Functions of a Forensic Scientist (3 of 3)

• The expert witness is called on to evaluate evidence

based on specialized training and experience that the

court lacks the expertise to do.

• The expert will then express an opinion as to the

significance of the findings.

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Evidence Admissibility: The Frye Standard

• The Frye v. United States decision set guidelines for

determining the admissibility of scientific evidence into

the courtroom.

• To meet the Frye standard, the evidence in question

must be “generally accepted” by the scientific community.

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Frye Not Absolute (1 of 2)

• However, in the 1993 case of Daubert v. Merrell Dow

Pharmaceutical, Inc., the U.S. Supreme Court asserted

that the Frye standard is not an absolute prerequisite to

the admissibility of scientific evidence.

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Frye Not Absolute (2 of 2)

• Trial judges were said to be ultimately responsible as

“gatekeepers” for the admissibility and validity of scientific

evidence presented in their courts, as well as all expert

testimony.

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Evidence Admissibility: The Daubert

Criteria (1 of 2)

• In Daubert, the Supreme Court offered some guidelines

as to how a judge can gauge the reliability of scientific

evidence:

– Whether the scientific technique or theory can be

(and has been) tested

– Whether the technique or theory has been subject to

peer review and publication

– The technique’s potential rate of error

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The Daubert Criteria (2 of 2)

– Existence and maintenance of standards controlling

the technique’s operation

– Whether the scientific theory or method has attracted

widespread acceptance within a relevant scientific

community

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Other Landmark Cases

– Kumho Tire Co., Ltd v. Carmichael determined that

the judge acts as a “gatekeeper” not only for scientific

testimony, but any expert testimony.

– Melendez-Diaz v. Massachusetts determined that

an expert witness must appear in person to provide

testimony in court so that the defense has an

opportunity to cross-examine the witness.

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Evidence Collection Training

• Many crime laboratories have “evidence technicians,”

trained by the crime lab staff, on 24-hour call for evidence

collection at crime scenes.

• Training ensures all pertinent evidence will be recognized

and collected properly.

• Where no formal training exists, familiarity can be gained

through lectures, tours of the lab, and evidence collection

manuals.

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Special Forensic Science Services (1 of 3)

• A number of special forensic science services are

available to the law enforcement community to augment

the services of the crime laboratory:

– Forensic psychiatry

– Forensic odontology

– Forensic engineering

– Forensic computer and digital analysis

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Special Forensic Science Services (2 of 3)

• Forensic psychiatry is an area in which the relationship

between human behavior and legal proceedings is

examined.

• Forensic odontology involves using teeth to provide

information about the identification of victims when a

body is left in an unrecognizable state; also investigates

bite marks, though this has become a controversial

method of analysis.

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Special Forensic Science Services (3 of 3)

• Forensic engineering is concerned with failure analysis,

accident reconstruction, and causes and origins of fires

or explosions.

• Forensic computer and digital analysis involves the

identification, collection, preservation, and examination of

digital evidence.

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