Intro to Criminalistics IP4

Criminalistics IP4

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Group Portion

Recovery Process

The evidence recovery process refers to the process at the crime scene where evidence is collected. The crime scene must be preserved as soon as the crime has occurred and the first police officer responds. Each piece of evidence located at the crime scene must be collected following standardized forensic methods to ensure the evidence does not become damaged when being processed. This systematic evidence collection process is done carefully following established policies.

The process begins with the preliminary crime scene survey/walk through followed by a determination of the evidence collection sequence that will be applied to this particular scene (Shiro, 2006). The most delicate evidence will be collected first. Some evidence is more delicate than other evidence and this evidence can be easily lost or destroyed making it imperative that it is collected first. Next the criminal investigator must collect evidence using the appropriate tools and equipment.

The evidence processing approach will depend on the type of evidence being collected. Hairs and fibers found at the scene will be collected using tweezers while dried blood is collected using a scalpel and then being placed in a clean, unused plastic container to be transported to the lab. Other evidence would be collected in a different manner. Any evidence being collected must be packaged separately to ensure the evidence does not become cross contaminated before reaching the lab. Once the evidence is collected and packaged it must be labeled and then transported to the lab.

The package will consist of a label including person's initials: the date and time it was collected; a complete description of the evidence and where it was found; and the investigating agency's name and file number (Schiro, 2006). It is important to clearly label any evidence and then transport the evidence directly the lab. For one the evidence may require immediate refrigeration if its blood evidence and secondly evidence must be transferred directly to the lab to avoid breaking the chain of evidence.

The chain of evidence begins when the evidence is preserved until it reaches the lab and it analyzed. When the evidence does not go directly to the lab there is a potential the chain of evidence can be broken. If the chain is broken the evidence may not be authenticated for court. Evidence must be authenticated by proving the evidence was collected from the scene and its exact location. It is further authenticated when the evidence is clearly documented and then transported directly to the lab.

Individual Portion

Recovery of DNA from the Crime Scene

DNA has become one of the important pieces of physical evidence that can be collected at a crime scene. DNA or deoxyribonucleic acid contains the genetic code of the individual that contributed the biological materials to the crime scene. DNA is contained in bodily fluids of the person as well as the bones, teeth, and hair. When a criminal suspect leaves behind, blood, urine, sweat, saliva, or any other biological material at the crime scene, it can be analyzed at the lab for a DNA profile than can then be matched to a criminal suspect.

Recovering DNA at the crime scene depends on the type of evidence that needs to be collected. Since DNA can be found in all types of biological evidence how it is collected will be dependent on the type and where the DNA is located (Warrington, 2009). For example if the evidence is a baseball bat the criminal scene investigator will look on the handle for evidence and the end of the bat. The potential evidence that can be located on the bat includes sweat, saliva, and skin tissues. The bat will be carefully packaged in order to ensure any DNA located on the bat can be preserved until it can reach the lab to be analyzed.

DNA is recovered from the scene on objects or the victim. Some objects are removable and should be packaged and sent to the lab but in other cases the DNA evidence is located on a surface and must be collected using standardized forensic collection methods. For example if there is dried blood on the floor it would be scraped with a scalpel wiped onto a piece of gauze and then placed in a plastic container. If the evidence left at the scene is semen it will be swabbed and then placed in an evidence envelope or if there is a large amount it will be wiped with gauze and then placed in a plastic evidence container or paper evidence bag. DNA should never be placed in a plastic evidence bag (Warrington, 2009).

The DNA collection process results in evidence that may be developed into a DNA profile in order to identify the person responsible for committing the crime or to identify a victim. When collecting evidence it is essential to protect the integrity of the evidence so it can be used in court. This means taking the needed step to make sure the DNA evidence does not become contaminated including wearing gloves and changing the gloves each time new evidence is collected and covering their faces in case the sneeze or cough. Once the evidence is collected and properly labeled it is transported to the lab to be analyzed.

References

Shiro, G. (2006). Collection and Preservation of Blood Evidence from Crime Scenes. Retrieved

September 14, 2014 from http://www.crime-scene-investigator.net/blood.html

Warrington, D. (2009). DNA Collection and Packaging. Retrieved September 14, 2014 from

http://www.forensicmag.com/articles/2009/04/dna-collection-and-packaging