COLLECTION OF BIOLOGICAL EVIDENCE.
The strength of any forensic evidence presented in a court of law highly depends on how effective its collection was and the sensitivity with which the evidence was handled after that. This previously ignored part of court proceedings seems to be catching up as evidenced with the professionalism witnessed in the police department lately.
Care is being taken during collection of this evidence just as required. Just to remind ourselves, biological evidence tends to deteriorate quite fast and get contaminated hence measures should be taken to prevent that and ensure its integrity.
The success in finding biological material depends upon the search method employed and also the integrity and state of the scene. It is important to adhere to the following guidelines while collecting the evidence:
- Wear the appropriate gear. These include full overalls, shoe covers, gloves and face masks.
- Seclude the area by marking it with tape to minimize human traffic.
- Start collecting evidence from outwards going inwards to capture as much evidence as possible.
- A range of light sources can be operated at fixed wavelengths and be used to detect stains.
- · Take as many photographs as possible at different angles( Thats a whole topic all together)
Methods used for collection will vary depending on the type of sample. For example,
- Searching a crime scene or items recovered from a crime scene for blood can be aided by use of luminol (3-aminophthalhydrazide)The chemical can be sprayed onto a wide area and will become oxidized and luminescent in the presence of haemoglobin, which is found in red blood cells. It is necessary to darken the area being searched in order that the luminescent are detected.
- Dry stains and contact marks on large immovable items are normally collected using a sterile swab that has been moistened with distilled water, in other cases scraping or cutting the material may be appropriate.
- Lifting from the surface using high quality adhesive tape is an alternative method for collecting epithelial cells.
- Liquid blood can be collected using a syringe. It can also be applied to FTA paper that is impregnated with chemicals to prevent action of microbial agents and stabilize the DNA.
- Smaller movable objects such as weapons, which might contain biological material should be packaged at the scene and examined in there controlled environment of a forensic laboratory.
TO BE CONTINUED…