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Criminalistics
The Crime Scene
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
ID of suspect- AFIS, CODIS databases
Investigative leads- paint, footwear
Reconstruction- “How it happened”
WHO RESPONDS TO THE SCENE
Detectives Investigating Case
Crime Scene Unit
Evidence Search & Processing
Identification Unit
Photography & Fingerprints
Medical Examiner
Homicides, Suspicious Deaths
Crime Scene Procedures
1. Protect scene
2. Search for physical evidence
3. Document scene- Notes, photos, measurements, sketch
4. Collect & preserve evidence
5. Transport to laboratory
6. Analyze evidence & reconstruct scene
SECURING THE SCENE
Barrier Tape - or other means (vehicles)
Secure all routes of access into scene
Log Book
Restrict entry
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
Supplemental Resources
K-9 Unit Metal Detectors Aviation/ Marine Bureau Emergency Services Lighting
Halogens Alternate Light Source/ UV
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
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
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)
Evidence Documentation
Roadmapping Stain Patterns
Photograph overall pattern using a scale of reference
Roadmapping Stain Patterns
Midrange
Close-up
SCENE DOCUMENTATION - 3•Crime Scene Notes
List Pertinent Information
Date, Time, Location
Personnel
Lighting, Weather
Observations-be objectiveItems Recovered:
Location of itemsPhoto taken?Time CollectedTest results, if any
SCENE DOCUMENTATION - 4
•Rough sketch
•Before collecting evidence
•Overhead or side view
•Compass heading
•Legend
•Measurements fm 2 fixed pts.
Coordinate
Baseline
N
north
east
Item
1
2
3
RP 1 RP 2
Baseline Method – Outdoor sketch
20 ft35
ft60 ft
18 ft
28 ft
20 ftTape measure
0 ft
N
RP 1 RP 2
Triangulation Method
N#1
100 ft
64 ft36 ft
Item fm RP1 fm RP
#1 knife 36’ 64’
Total Station
SCENE DOCUMENTATION – 4Finished CAD sketch
Homicide Investigation
CC# 08-246801
30 Campus Ct, Riverhead
RB 02-10-08
Legend
1 Cartridge
2 Bloodstain
3 Cigarette butt
4 Ski mask
5 Beer can
Search Patterns
Line (Strip) Method Large outdoor scenes
Uneven terrain
Uses several searchers
Move at same pace
Mark evidence when
found
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
Search Patterns
Quadrant/Zone Method
Large outdoor scenes
Divide scene
Diagram quadrants
Collect evidence within the
quadrant
Air crash
Rooms in house
Automobiles
Search Patterns
Spiral Method
Indoor scenes
Start at perimeter or
center
Move in circular pattern
Locating Physical Evidence
Primary Scene- where principal activity occurs ie. body, cartridge casings, ransacked bedroomTarget area, natural or forced entry & exit points
Secondary Scene- associated locationsVehicleBody dumpedDumpster, garbage cansStaging areaStorm drainsPerp’s residenceNeighbor’s yard
Triage processing if evidence may be compromisedTry to locate the Primary Scene ASAP !!!
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
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
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
Chain of Custody
Authenticates the integrity of the evidence Who had the evidence ? When did they have possession of it ?
PROVE IT!
Security Tape
Jane Doe
EVIDENCE COLLECTION
Fingerprint Evidence
Do not obliterate prints
Package loosely in boxes
Handle only unprintable areas
Do not package in plastic bags
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
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
2
34
5
6
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
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
Reference Standards/Exemplars
Material from KNOWN source is used for comparison to QUESTIONED evidence
GlassPaintCarpetClothingBuccal swab, blood sampleHair
