Trace Evidence In Criminal Investigation

Upon the arrival of the law enforcement to the crime scene, it is essential that measures are taken to protect the crime scene, and subsequently to protect any potential evidence, in the manner that it was left at the scene. Crime scene protection not only includes cordoning off the area where the crime is believed to have occurred but also includes documentation of all of those present at the scene including law enforcement personnel as well as noting anything that may look out of place. This allows investigators to conduct a preliminary examination of the crime scene to aid in constructing a hypothesis as to the events that have taken place and the later reconstruction of the crime scene. The investigators then begin the process of sketching,
Some trace evidence of this case includes the fragments of cut grass on the victim’s thighs and abdomen; the grass fragments entangled with the victim’s pubic hair; swaps of the dirt soiling on the victim’s left thigh and both buttocks; and any loose twigs or leaves in the victim's hair. These samples of trace evidence can be compared to examples found at the crime scene to determine that a struggle, in fact, took place at the scene and that this isn’t just a dumping ground for the body. Crime scene investigators may take swab samples of the blood evidence present on the victim’s left arm, left breast, and around the nose and mouth to determine if the blood originated from the victim for if it belongs to another source. This can be done by comparing the DNA profile from the swabs to a known DNA profile of the victim. If still wet, the blood swaps should be transported to a sterile lab area in separate plastic containers and removed so the evidence can air dry before being placed in a separate paper or plastic envelopes for submission to the forensic laboratory. At the crime scene, investigators will also photograph and bag the victim’s hands to preserve the dirt evidence embedded beneath the
The vaginal, anal and oral swab samples are key to determining if a sexual assault has occurred in this case. Additionally, and foreign hair samples found on the victim, particularly if found in the pubic area, as well as the collected fingernail scrapings, may also play a vital role a circumstantial evidence pointing towards sexual assault in this case. The biological blood sample found on the victim should be compared to a controlled sample to determine its origin. Similarly, any hair found on the victim can be compared to a controlled sample from the victim. Any fibers found on the deceased can be compared to the clothing items that were found at the scene, as well as the grass or soil samples found can be compared to controlled samples collected from the crime scene concluding that the struggle between the victim and the assailant occurred at the crime