Processing a Crime Scene: Physical Evidence.
Physical Evidence Collected at the Crime Scene.
- Shell Casings
Shell casings are a type of ballistic evidence. The casings are used to identify the type of weapon used to discharge the bullet. The markings on the shell casing are specific to tell which caliber it is from, therefore narrowing down the possible type of gun. However, shell casings alone cannot identify a particular weapon. The shell casings at the scene were collected and put in separate envelopes. The collection method was chosen as a means of preventing the mixing of evidence (Zannin & Huber, 2017).
- Bloody fingerprints
A bloody fingerprint is a type of plastic print. These prints are made when a person’s finger touches a soft or malleable surface, hence forming an indentation outlining their fingerprint. Bloody fingerprints are the most reliable form of physical evidence that places an individual at the crime scene. Both the print and DNA from the blood can be matched to their owner.
The bloody fingerprints at the crime scene were lifted using clear and adhesive tape and putting it on a lift card to keep the print intact. If the prints which could not be lifted were photographed using a Polaroid CU-5 camera. The photographs were one to one.
- Drug paraphernalia
Many types of drug paraphernalia can be found in a crime scene. The kind of apparatus can indicate the type of drugs used by the persons involved in the crime. Syringes are generally connected to drugs like crack and heroin while smoking devices are linked to marijuana and others.
Drug paraphernalia was discovered at the crime scene—a tube-like smoking device and a plant-like substance. The device was put in a brown paper bag while the plant substance was placed in an envelope. The collection method was chosen as a means of preserving any evidence that may be found on the device and substance.
- Blood
Blood is a reliable type of physical evidence since it can be used to narrow down the pool of suspects and positively identify the perpetrator when they are found. The DNA tests ran on the blood can positively pinpoint the groups (ethnicity, family relations, etc.) of an individual. Comparing the DNA found at the scene to that of a suspect can place them at the scene. Bloodstain patterns can also be used in the reconstruction of a crime scene (Miller, 2002).
There were droplets of dried blood found at the crime scene. The collection method used was to absorb the blood with threads (1/2 inch) dipped in distilled water, air- drying the blood-soaked threads and putting them in packaging envelops.
- Tire tracks
Tire tracks can be used to match a type of car to the crime scene. Investigators can use the kind of car o narrow down their suspects. The collection method appropriate for this type of evidence is photographing. A one-to-one photograph should be taken at a 45-degree angle from the tire track impression (Touroo & Fitch, 2018). The pictures are easier to use since they can be used to compare tire tracks of suspect’s vehicles at any location.
Other Possible Physical Evidence.
- Broken fingernails.
Fingernails can be matched to their owner. Natural nails have unique striations specific to every person. A broken fingernail can be used to place a suspect at a crime scene if the striations match. The best method of collection is putting the broken nail in a paper packet, then placing the paper packet in an envelope. The process of collection prevents any contamination while preserving the nail.
- Hair
Hair strands found at a crime scene can be used to narrow down the number of suspects. The characteristics of a strand of hair are not unique to a specific individual, but it can be used to rule out those who do not have these characteristics. Furthermore, if the strand has a root sheath, DNA can be collected from the sheath (Touroo & Fitch, 2018). The DNA can then be compared to that of a suspect and, therefore, place them at the crime scene if the match is positive.
Objects used to inflict injury on the victim are generally called weapons. By these definitions, obvious items such as guns and everyday items like knives and bats are all weapons if they are material to the incident under investigation. Other forms of physical evidence can be found on the weapons or linked to them. Examples of such evidence are fingerprints, blood, or gun powder residue (found on the suspect). The best method of collection is picking up the weapon using gloves and placing them in a paper bag. Sharp weapons should be wrapped in stiff cardboard before placing them in paper bags. Firearms should be photographed and declared safe before storage in the crime lab.
References
Miller, M. T. (2002). Crime scene investigation. In Forensic Science (pp. 143-164). CRC Press.
Touroo, R., & Fitch, A. (2018). Crime Scene Findings and the Identification, Collection, and Preservation of Evidence. In Veterinary Forensic Pathology, Volume 1 (pp. 9-25). Springer, Cham.
Zannin, A., & Huber, L. (2017). Crime Scene Investigation. In Manual of Forensic Science (pp. 1-20). CRC Press.