Unit #2 – Crime Scene Basics Lesson #3 – Evidence Collection/Processing Learning Goals Know: Steps taken at the crime scene Understand: Reasoning behind steps and precautions Be Able To: Explain and perform basic crime scene investigation and evidence collection

Trace Evidence – The Search The lead investigator will designate a search pattern appropriate to the crime and the scene. Here are some options… Inward/Outward Spiral Parallel/Grid Quadrant A single investigator searches each quadrant. They may then switch quadrants and repeat. A line of investigators searches in one direction. In a grid they then go in the other direction. A single investigator starts on the inside/outside of the scene and slowly spirals out/in. Good for areas that can be clearly cut into fours – square room, car, etc. Good when the area is clearly defined and a lot of people are on hand. Good for open areas or for scenes with limited number of investigators.

Trace Evidence – Collection Tools We are finally ready to collect the evidence. Supplies you need… Forceps/ Tweezers Picking Up Evidence Swabs Evidence Tape Vacuum Gloves

Trace Evidence – Storage Storing Evidence Small trace evidence – HAIR, FIBER, SHELL CASING Small envelopes Plastic pill bottles Small cardboard boxes Glass vials Use an appropriate container for each piece of evidence

Trace Evidence – Storage Storing Evidence Larger evidence – WEAPON, DRINKING GLASS, CLOTHES Manila envelopes (not white mailing envelopes) Paper bags Plastic bags Wet or stained items – BLOOD, SEMEN, ETC. Air-dry in non-airtight containers. Avoids molding.

Trace Evidence – Reference Samples A piece of trace evidence is only useful if there is something to compare it to. For example, a piece of hair from the scene can only be matched to other hairs. Collect “reference” samples from: VICTIM SUSPECT(S) OTHERS RELEVANT TO THE CASE

Other Trace Evidence Examples of “other” trace evidence that may be discussed in other units include but are not limited to… fingerprints footprints/impressions tool-marks bullet holes documents