Crime Scene Processing Forensics 4

Definition of “Crime Scene” Any area where potential evidence is found, passed through or interacted with Primary Crime Scene –Location of original or first criminal act Secondary Crime Scene –Location of subsequent criminal acts Example: The site of a homicide vs. the location where the body is left

General Processing Procedures Secure and protect the scene Record the scene Search for evidence Collect and package evidence Submit evidence for analysis Reconstruct scene

1: Secure the Scene Often difficult for the first responder in light of other duties Observe immediate scene –Identify major physical features and safety concerns –Persons present –Paths into and out of area –Likely boundaries of primary scene –Restrict access

2: Record the Scene Note taking is the most important aspect of any investigation –Must be legible –Must be detailed –Must be specific –Must never be discarded Many investigators use pocket tape recorders

2: Record the Scene Date, time and weather information of crime and investigation Type of crime General location and description of crime scene Names of all investigators, witnesses, police officers, etc. Measurements of important features of scene and surrounding area Preliminary sketches, photos and/or video Have we entered the secured area yet?Have we entered the secured area yet?

3: Search for Evidence General survey first to pick out notable characteristics More photos and sketches –Photos should be close-ups, mid-range and wide angle –Use measuring devices where applicable especially on close-ups –Rough sketch at crime scene, scaled sketch later Search must be systematic and specific Generally work from outer edges into center Use extreme caution when entering site

3: Search for Evidence Search, do not collect evidence –Leave markers for later retrieval of evidence –Tape, flags, markers, etc. 3d Think 3d, evidence is not always on the ground

3: Search for Evidence Six major search patterns –Link Method Point to point – one item leads to another “Bread crumbs” –Grid Method Very complete but time/manpower consuming –Line/Strip Method Often used in very large areas Again, personnel intensive

3: Search for Evidence Six major search patterns –Zone Method Often used in buildings A single room might be a “zone” –Spiral Method Search spirals out in circles from center of incident –Wheel/Ray Method Search fans out in straight lines from center of incident Limited applications

4: Collect and Package Use as few people as possible –Limits collection techniques, contamination and mistakes Collect “most fragile” evidence first Method of collection varies with type of evidence –This includes the containers evidence is collected in Sealed completely and identified –Keep a separate log of all evidence Only once all evidence is collected is the scene “released” to appropriate personnel

5: Submit for Analysis Often not completed by collecting investigator May require specific processes or facilities

5: Submit for Analysis Crime Labs Can be public or private Public labs run by national/state/local law enforcement agencies –4 US Government Labs FBI ATF DEA USPS Private labs run by person or corporation –May specialize in one area only (Ex: toxicology) –Retest evidence already examined by public lab

6: Crime Reconstruction Once analysis is complete, reconstructions often follow May involve complex live/computer simulations Investigators try to recreate exactly what happened –Very popular in TV’s “CSI”