Intro to Criminalistics IP2

Collecting Evidence

Criminalistics IP2

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Collecting Evidence at the Crime Scene

Physical evidence is pivotal to solving crimes and for many juries proving the guilt of the criminal suspect. Properly collecting the evidence will protect it from becoming damaged or destroyed at the crime scene and will ensure it admissibility in the court process. Physical evidence us especially important at the crime scene. This evidence points to what happened to the victim and who is responsible for committing the crime. The current crime scene contains evidence of a homicide. The evidence located at the scene includes drying blood on the floor,, a handgun and several shell casing near the victim, and several hairs that are still in the hand of your deceased victim.

Collecting Drying Blood

Blood is important evidence that can yield important information, such as a DNA profile. This DNA profile can be matched to a criminal suspect providing the court with irrefutable evidence of guilt. Blood evidence can also describe what occurred at the scene. Before collecting drying blood the evidence must be documented. Documenting the blood involves carefully photographing the evidence to scale before beginning the collection process. Photographing the evidence where it was located at the scene and from every angle will ensure the evidence can be validated and then as evidence in the court case.

Drying blood is delicate evidence that must be collected following tried and true collection methods. If possible the drying blood should be left to completely dry and then be scraped up using a scalpel and placed in an evidence envelope. The blood evidence still drying on the floor will be wiped up by the criminal investigator using a gauze pad (Shiro, 2006). The gauze pad will then be placed in an evidence envelope and carefully labeled before being transported to the crime scene.

Properly labeling the evidence before it leaves the scene heading to the crime lab is very important. This label provides investigators with important information about the crime scene that will be relayed in a court of law. On the label will be the name of the crime scene investigator, time and date, where evidence was located, and how it was collected. When this information is missing the evidence cannot be authenticated in a court of law. When evidence cannot be authenticated through the chain of evidence it will not be eligible to be used as evidence against the criminal defendant in a court of law.

Once the evidence reaches the lab a serologist will analyze the blood in order to try to develop a DNA profile. The serologist will conduct presumptive tests first to identify the specific fluid and to conduct other preliminary tests (McDonald, 2012). These tests will provide information about blood type and the type of biological evidence before conducting a DNA analysis. This analysis will be pivotal to potentially providing physical evidence that will point to the guilty offender.

Handgun and Shell Casings

At the murder scene crime scene investigators have located a handgun and a shell casing. The handgun and shell casing are important to the murder case especially if the handgun was used to kill the victim. Handguns are carefully collected by using a gun and picking up the gun by the rubber grip of the gun. The criminal investigator will remove any bullets or clips from the gun and package them in separate evidence envelopes. A gun should never be collected with a pencil or any other object in the bore of the gun (Schiro, 2006). It can damage the cylinder of the gun making harder to determine if the gun has been recently fired and if the gun matches the shell casings left at the scene.

Any bullets in the chamber or loose bullets should be packaged separately (Murnaghan, 2014). Shell casings should be collected and individually place in an evidence envelope which can also include placing the shell casing in separate pill bottles. Similar to the drying blood evidence, before collection the evidence should be carefully photographed and once collected using standardized collection methods should carefully label each piece of evidence before sending it to the crime lab. Once the gun and the shell casings reach the lab they will e analyzed by a ballistic expert for evidence that the gun fired the bullets recovered from the body and to determine if the shell casings match the gun located at the crime scene.

Recovering Hairs

At the crime scene hairs have been located in the hand of the victim. These hairs must be carefully photographed before being collected. The hairs in the hand so of the victim will be collected with tweezers and individually wrapped before being placed in the evidence envelope. Thus is after they are first carefully photographed. Each envelop bag will be carefully labeled before being transported to the forensic lab hair can yield important DNA information but only if the hair contains the important hair shaft. The hair shaft contains material than can be tested for DNA. The hair can also yield other important information such as the race and gender of the person the hair belongs to.

Conclusion

The crime scene yields important evidence that can provide crime scene investigators with an idea of what happened at the crime scene and more importantly point to the guilty offender. The evidence left behind at the murder scene could potentially identify the suspect responsible for the homicide as well as provide evidence for the prosecution in a court of law. When evidence is not properly collected or the chain of evidence is broken the evidence is at risk for being rejected from the court process due to a lack of ability to authenticate.

References

Murnaghan, I. (2014). How Can a Bullet be identified from a Particular Gun? Retrieved August

30, 2014 from http://www.exploreforensics.co.uk/how-can-bullet-be-idenitied-from-particular

Shiro, G. (2006). Evidence Collection Guidelines. Retrieved August 30, 2014 from

http://www.crime-scene-investigator.net/collect.html#3

McDonald, J. (2012). Forensic DNA Analysis. Retrieved August 13, 2014 from

http://www.ncbi.nlm.nih.gov/pubmed/22693781