Unit 2 Crime Scene Basics Lesson 3 Evidence

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 Inward/Outward Parallel/Grid Quadrant Spiral pattern appropriate to the crime and the scene. Here are some options… AAsingle line single ofinvestigatorsearches starts searches oneach the in one quadrant. inside/outside direction. They. In ofmay athe grid then scene they switch and then go quadrants slowly in the spirals other anddirection. out/in. repeat. Goodwhen for areas open the areas thatiscan or clearly for be defined scenes clearly cut with andinto alimited lotfours of people number – square of room, investigators. on hand. car, etc.

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

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