Physical Evidence Any object that can establish that a crime has been committed or Provide a link between a crime and its victim or Between a crime and its perpetrator

12 stages of a crime scene search 1. Advanced Preparation 2. Approach the scene 3. Secure and protect 4. Initiate a preliminary survey 5. Evaluate the physical evidence 6. Prepare a narrative description 7. Photograph the scene 8. Prepare a sketch 9. Conduct a detailed search 10. Record and collect all the physical evidence 11. Conduct a final survey 12. Release the crime scene

Who is Involved in a Crime Scene? First officer Detective Crime Scene Investigator Crime Scene Reconstructionist

First Officer 1. Call for medical assistance if injuries occurred 2. Secure the scene 1. Look for perps and make arrest 2. Isolate large area with rope/tape 3. Keep all unauthorized personnel out of crime scene 4. Make sure no one touches anything 3. Call Criminal Investigators (ID unit) 4. Begin crime scene log and keep until after scene is processed 5. Make help detective question and transport witnesses to police station

Detective Question witnesses Transport witnesses to station to make a formal written statement Develop theories on witness statements

Crime Scene Investigator Lead Investigator In charge of scene, determines boundaries and perpetrator’s entrance and exit Record the scene Sketching, notes, and photography Collect and package any evidence Later, they will testify and demonstrate all evidence at trial

Recording a crime scene Photography Unless there are injuries, nothing may be altered until all photographs are taken What to photograph? points of entry/exit Adjacent rooms/area Entire room from various angles Close up of injuries/weapons Under body must be photographed after body is removed

Make sure to use photo log for documentation Utilize various views of the scene Photograph all evidence prior to collection Digital Media is cheap, USE IT!!!! Take pics from eye level

Special case: Corpse Document with photos and note the precise position, location, and injuries. Send for medical examiner who will pronounce the victim dead Obtain victim’s clothing as evidence

Sketching the crime scene Make a rough sketch Include specific location, date, time, case identifier, preparer, weather and lighting conditions, scale or scale disclaimer, evidence Important measurements, legend, and key Objects are located from 2 measurements from fixed points

Finished Sketch must be to scale, include everything seen in rough sketch Also include compass reading

Note taking Quick descriptions of the crime scene May also be video recorded

Searching for Evidence Searching systematically Subdivide into segments Circular Grid Make sure to search entries and exits too Vacuum critical areas

Evidence Collection Evidence must be collected in the correct methods to be admissible in court

Blood Use gauze or cotton swab to obtain a sample Allow to air dry and send to lab immediately Put in brown paper bag or box and seal. DO NOT use plastic containers

Dried Blood If possible place entire stained area in brown paper bag. If you can not do so, scrape dried blood onto clean paper, then put in envelope Do not mix stains, place each stain in a different envelope NEVER moisten stain

Seminal Fluids Place in paper bags NEVER in plastic bags

Hair/Fibers All hair should be collected in small bindles and place in larger envelopes

Firearms/Weapons Should be put in gun box Knifes should be put in knife box

Overall rules If it is DNA evidence, use paper MOISTURE BAD It will increase DNA breakdown

Points of Interest Homicide Look for hair, weapons, fibers, cross-transfer, signs of struggle Burglary Tool marks for point of entry Hit and Run Undercarriage for cross- transfer Blood, tissue, hair, paint and broken glass on victim

Chain of custody List of all people came in contact with evidence Each container has collector’s initial, location of evidence, and date of collection

Obtain Reference/Control Sample Physical evidence whose origin is know at comparison to evidence found at crime scene Buccal Swab – swab of inner cheek Substrate control – uncontaminated substance, used in arson or blood stained carpets

Autopsy Make sure to take fingernail scraping Look for pathological and toxicological evidence Head and pubic hair, presence of blood Take vaginal, anal, and oral swabs Recover bullets and hand swabs for gunshot residue Pathologist – ensure correct cause of death

Time of death Determined by rate of composition Rigor Mortis Muscles become rigid within first 24 hours, but stop after 36 hours

Livor Mortis/Lividity/Hypostasis Blood settles in part of body closest to the ground Happens in first 12 hours

Algor Mortis Body temp continually loses heat at a rate of 1 – 1 ½ degree F per hour

Forensic Anthropology Look at skeleton to reveal Sex Age Skeletal injury of victim Also help reconstruct facial features

Forensic Entomology Study of insects and their life cycle Help estimate time of death Blowflies will lay eggs Eggs will hatch into pupae stage Effected by environmental conditions Only give an estimated time of death