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Criminalistics

Criminalistics

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Criminalistics

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Presentation Transcript

  1. Criminalistics The Crime Scene

  2. Information from Crime Scene & Physical Evidence • Corpus Delecti- facts that establish crime occurred • Modus Operandi- perpetrator’s “signature” • Link person to person, object , scene • Prove/disprove witness, victim, suspect statements • IDof suspect- AFIS, CODIS databases • Investigative leads- paint, footwear • Reconstruction- “How it happened”

  3. WHO RESPONDS TO THE SCENE • Detectives Investigating Case • Crime Scene Unit • Evidence Search & Processing • Identification Unit • Photography & Fingerprints • Medical Examiner • Homicides, Suspicious Deaths

  4. Crime Scene Procedures • Protect scene • Search for physical evidence • Document scene- Notes, photos, measurements, sketch • Collect & preserve evidence • Transport to laboratory • Analyze evidence & reconstruct scene

  5. SECURING THE SCENE • Barrier Tape - or other means (vehicles) • Secure all routes of access into scene • Log Book • Restrict entry

  6. Crime Scene Safety • Wear protective clothing and gear • Always use latex or nitrile gloves • Be alert to sharp objects: Knives, syringes, glass, etc. • Don’t reach where you can’t see!!! • Don’t eat, drink, spit or smoke within the scene • Universal Precautions – body fluids • Bleach or dispose of equipment contaminated with blood

  7. Supplemental Resources • K-9 Unit • Metal Detectors • Aviation/ Marine Bureau • Emergency Services • Lighting • Halogens • Alternate Light Source/ UV

  8. EVALUATING THE SCENE • Walk Through • One member of each group • Determine safe areas to walk • Identify important aspects of the scene • Develop a plan of action, initial theory

  9. SCENE DOCUMENTATION - 1 • Video Photography – 3D Orientation • Introduction- placard or audio • Start outside scene • Walk through scene • Overall then close-up on important items • Continuous taping; no sound, no editing

  10. SCENE DOCUMENTATION - 2 • Still Photography • Work from outside to inside • Overall, midrange, then close-ups (with & without ID tag) • Examination Quality Photos of Impression Evidence • Overlap photos for perspective/context • Document evidence with tags and scale, cones, flags, placards • Photo Log: date, time, roll#, exposure, settings, description of item • Patterns (“roadmap” w/ references)

  11. Evidence Documentation

  12. Roadmapping Stain Patterns Photograph overall pattern using a scale of reference

  13. Roadmapping Stain Patterns Midrange Close-up

  14. SCENE DOCUMENTATION - 3 • Crime Scene Notes • List Pertinent Information • Date, Time, Location • Personnel • Lighting, Weather • Observations-be objective • Items Recovered: • Location of items • Photo taken? • Time Collected • Test results, if any

  15. SCENE DOCUMENTATION - 4 north • Rough sketch • Before collecting evidence • Overhead or side view • Compass heading • Legend • Measurements fm 2 fixed pts. • Coordinate • Baseline east N Item

  16. Baseline Method – Outdoor sketch 2 N 3 1 28 ft 20 ft 18 ft Tape measure 0 ft 35 ft 60 ft 20 ft RP 1 RP 2

  17. Triangulation Method Item fm RP1 fm RP #1 knife 36’ 64’ N #1 64 ft 36 ft 100 ft RP 1 RP 2

  18. Total Station

  19. SCENE DOCUMENTATION – 4 Finished CAD sketch • Legend • Cartridge • Bloodstain • Cigarette butt • Ski mask • Beer can Homicide Investigation CC# 08-246801 30 Campus Ct, Riverhead RB 02-10-08

  20. Search Patterns • Line (Strip) Method • Large outdoor scenes • Uneven terrain • Uses several searchers • Move at same pace • Mark evidence when found

  21. Search Patterns • Grid Method • Move back and forth in parallel lines • When the area has been covered, switch to perpendicular direction • Each area viewed twice, different perspective

  22. Search Patterns • Quadrant/Zone Method • Large outdoor scenes • Divide scene • Diagram quadrants • Collect evidence within the quadrant • Air crash • Rooms in house • Automobiles

  23. Search Patterns • Spiral Method • Indoor scenes • Start at perimeter or center • Move in circular pattern

  24. Locating Physical Evidence • Primary Scene- where principal activity occurs • ie. body, cartridge casings, ransacked bedroom • Target area, natural or forced entry & exit points • Secondary Scene- associated locations • Vehicle • Body dumped • Dumpster, garbage cans • Staging area • Storm drains • Perp’s residence • Neighbor’s yard • Triage processing if evidence may be compromised • Try to locate the Primary Scene ASAP !!!

  25. Locating Physical Evidence • Ceiling- blood, tissue, projectiles • Drapes- blood, fibers • Trash cans- gloves, weapons • Refrigerator- food • Toilet- hairs, urine, fingerprints, • Missing items- investigative information • Location of PE- may be relevant if suspect was resident or frequented location on previous occasions

  26. Locating Physical Evidence: Bodies • Another type of “Scene” • Document with notes and photography • Sexual Assault Kit, fingernail scrapings • Fibers, hairs, dried stains on body • Gunshot residue • Accelerants, other Trace Evidence • Clothing, personal items

  27. EVIDENCE COLLECTION • Document evidence prior to collection • Package each item separately • Place evidence in container at scene • Prevent loss, alteration, contamination! • Mark with identifying #, initials, date • Chain of Custody !!!!!!! • Secure the evidence at the time of collection

  28. Chain of Custody PROVE IT! • Authenticates the integrity of the evidence • Who had the evidence ? • When did they have possession of it ?

  29. Security Tape

  30. Jane Doe

  31. EVIDENCE COLLECTION • Fingerprint Evidence • Do not obliterate prints • Package loosely in boxes • Handle only unprintable areas • Do not package in plastic bags

  32. EVIDENCE COLLECTION • Biological Evidence • Paper containers only • If wet, air dry ASAP • Collect item with stain, if possible • Scrape into paper fold • Collect stains with damp swab

  33. EVIDENCE COLLECTION • Firearms Evidence • Assume gun is loaded! • Document location of ammunition in weapon • Package ammunition separately • Make sure that all weapons are clear 1 6 2 5 3 4

  34. EVIDENCE COLLECTION • Trace Evidence • Paint - Scrape into paper fold • Static can cause loss! • Glass - Package to protect: • Evidence - so it doesn’t break • Handler - to avoid injury • Knives - Package to contain sharp edges

  35. LEGAL ISSUES • Search Warrant not required • Search of premises for suspect or victim • To prevent immediate destruction of evidence • Consent • Upon arrest, search of person

  36. Reference Standards/Exemplars • Material from KNOWN source is used for comparison to QUESTIONED evidence • Glass • Paint • Carpet • Clothing • Buccal swab, blood sample • Hair