INTRODUCTION TO CRIME SCENE INVESTIGATION

OBJECTIVE DISCOVERY, DOCUMENTATION, AND COLLECTION OF EVIDENCE THAT WILL ASSIST THE INVESTI- GATION IN ANSWERING THE TYPICAL WHO / WHAT / WHERE / WHEN / WHY / HOW QUESTIONS

TYPICAL FLOW OF A HOMICIDE INVESTIGATION Initial call (911, etc.) Dispatch First responder EMS Investigator CSI Medical Examiner Other personnel

FIRST RESPONDER Clear the scene—arrest the suspect if appropriate Assess the situation See if someone needs medical attention—notify dispatch

FIRST RESPONDER Call for backup if needed Call for CSI, Investigator, etc. Secure the scene Identify and detain witnesses

EMS PERSONNEL Check victim for vital signs; transport if alive, back out of scene if deceased

INVESTIGATOR Get information from first responder Obtain warrant or consent Assess crime scene, brief CSI Identify victim, if possible

INVESTIGATOR Interview witnesses Interrogate suspect if available Identify associates or family of victim Follow leads that result from the crime scene investigation

CRIME SCENE INVESTIGATOR Obtain information from investigator Assess scene; re-set perimeter if needed Photograph and videotape scene

CRIME SCENE INVESTIGATOR Search scene for evidence Document evidence Process evidence if appropriate Collect evidence

CRIME SCENE INVESTIGATOR Take measurements Transport evidence, submit to lab or property Produce diagram and report

MEDICAL EXAMINER AGENT / INVESTIGATOR Assess body, bag hands if needed Take possession of body Secure body (white sheet, body bag) Arrange transport to morgue

PATROL SUPERVISOR Coordinate patrol activities –Protecting scene –Identifying witnesses –Canvassing neighborhood –Assisting with search as needed Interface between patrol and others

DEPARTMENT SPOKESPERSON (if appropriate) Provide information to media as appropriate, after discussing with investigator

MEDIA RELATIONS The media are serving a public interest; don’t keep them from doing their job as long as they don’t keep you from doing your job. Release details that you need the public to know (description of suspect or vehicle, for example)

MEDIA RELATIONS Protect information that you need to remain confidential Hidden details become very important if a suspect confesses: –Tests the confession –Bolsters the confession if it is accurate

SEARCH METHODS Line search Grid search Spiral search Quadrant / zone search Wheel spoke search

CRIME SCENE EQUIPMENT Cameras; conventional and digital Videorecorder Tripods Batteries, film, videocassettes Containers (sacks, envelopes, plastic bags, boxes, etc.) Fingerprint equipment and supplies Protective equipment, gloves, booties

CRIME SCENE EQUIPMENT Measuring tools: tapes, roller tape, rulers, angle gauges, etc. Markers, chalk, etc. Packaging tape, duct tape, etc. Casting materials (dental stone, etc.) Magnifiers Tools: saws, screwdrivers, wrenches Lighting, flashlights, illuminators

BORROWED EQUIPMENT Fire Department usually very well equipped with ladders, lighting, respirators, etc. Other city / county service groups have additional resources Utilities

TYPES OF EVIDENCE Fingerprints Other impression evidence –Footwear –Tool marks –Tire treads Bloodstains

TYPES OF EVIDENCE Other body fluids (sexual assault scenes) Firearms evidence –Firearms –Bullets –Cartridge cases –Gunshot residues –Bullet holes –Ricochet marks

TYPES OF EVIDENCE Trace evidence –Hairs –Fibers –Paint –Soil –Construction materials –Textiles –Metal filings

TYPES OF EVIDENCE Botanical materials Documentary evidence Ignitable liquid residues (fire scenes)

OTHER IMPORTANT POINTS Legality of search Preservation of evidence –At scene –During storage Chain of custody