CRIME SCENE

Physical Evidence and the Crime Scene

• Crime Labs “run” on physical evidence

• P.E. = ANY/ALL objects that:– Establishes that a crime has occurred– Link a crime scene to a victim/suspect

• Evidence is ONLY effective, if RECOGNIZED & COLLECTED correctly– CANNOT collect ALL objects– Collector’s NEED knowledge of lab’s techniques,

limitations, capabilities

Physical Evidence and the Crime Scene

• “GOOD” police work + accurate analysis of IMPORTANT evidence– NOTHING can salvage poorly “chosen” or collected

evidence– Proper training CAN ensure competent work

• Specially-trained CSI’s• Trained officers (special workshops)

• Limits on evidence collection– Not all scenes allow for P.E. removal– Limited resources/personnel

Secure & Record the Crime SceneSecure & Isolate Crime Scene

• Evidence MUST be preserved/recorded in “original” state

– Failure to protect/record scene accurately may, result in destruction/reliability of evidence

• MISLEADING or CONTAMINATED

Secure & Record the Crime Scene• Secure & Isolate Crime Scene

– 1st arriving officer secure/preserve crime scene• Arrest perpetrator• Get medical aid, if needed• Exclude UNNECESSARY individuals

– Isolate area (barrier/ropes w/guards)– High-profile cases = MORE “unnecessary” attention

» Media & high-level officials» Easy destruction

• Find “perp’s” entry/exit• Recognize “obvious” evidence first

– Document/photograph

RECORD THE SCENE• limited time to work “untouched” crime scene

• Good records aid in investigations & court presentations– 3 methods

• photography• sketches• notes

ALL should be used, but photos NOT always possible

RECORD THE SCENEPHOTOGRAPHY

• scene MUST be unaltered– photos taken @ ALL angles– changes = inadmissibility– removed objects NOTED, NOT replaced

• crime scene/adjacent areas photographed– close-ups [angles] of objects/persons NEEDED

• scales used when needed

• Digital photos/computers = details

• Videotaping > becoming popular

• Types: UV, IR, X-ray

RECORD THE SCENESketches

• Early phase > rough sketch = accurate dimensions & locations of important objects– quickly done [No skill/time]– accurate distances [tape measure], compared to 2 fixed points– objects designated by letter/number– compass legend included

• Finished sketched > aesthetic appearance– use templates/drafting tools– drawn to scale– include info. from rough sketch – Shapes may be used to represent evidence {keep it labeled}

• MUST have a compass legend– CAD & other computer software used

• Add blood spatter or zoom in on objects

RECORD THE SCENENotes

• Notes = CONSTANT process @ C.S.– detail description of scene

• locations, time (identification), who & how discovered and packaged, and where evidence sent.

• MUST be thorough > to “jog” memory• Tape recording helps [faster]• video narration

– tapes MUST be transcribed

Dealing with Physical Evidence

• Preliminary Walk-through

• Thorough P.E. search

• Correctly collect, preserve & store evidence– Keep it from being contaminated or tainted

• Developed procedures MUST be followed

Dealing with Physical evidenceSystematic Searches

• Never overlook evidence at a scene– Even if circumstances are “obvious”– Overlooking evidence may lead to “cover-up”

allegations

• Searches tend to be led by the in-charge investigator– Forensic scientists role usually starts once evidence is

submitted to lab– Some agencies have specially-trained personnel that

searches the crime scene (CSI’s)• Have equipment, knowledge, & skills to locate & collect P.E.

Dealing with Physical evidenceConsiderations in Searching a crime Scene

• Search will depend on:– Location & size of crime scene– Suspect’s & Victim’s actions

• Have a supervisor whenever possible

• Circumstances of a crime dictate what will be “looked” for

• Searches of vehicles MUST be done in a systematical way that’s been well-planned

Dealing with Physical evidenceCollect Physical Evidence

• P.E. can be microscopic (trace) to massive (in size)• Crime scene (critical) areas – vacuumed/evidence submitted to lab• Search BEYOND crime scene > for evidence (Autopsy)

– Tissues/Organs submitted for pathological & toxicological tests– Evidence collected during autopsy & sent to lab:

• Victim’s clothing• Fingernail scrapings• Head/pubic hairs• Blood (CAN profile)• Vaginal, oral, anal swabs (sex-related crimes)• Recovered bullets• Hand swabs for gun residue analysis

• If body is buried, efforts to obtain “good” evidence may be pointless

• Delay = loss of forensic value [of evidence]

Dealing with Physical evidenceCollection & Packaging of Physical

Evidence• P.E. MUST be collected & processed, as to prevent alterations in evidence [from original state to the lab]

• MAIN changes in evidence:– Contamination, breakage, evaporation,

bending/stretching, or loss of evidence• Evidence MUST be kept in ORIGINAL condition• When possible, ALL evidence (blood, hair, fibers)

should be submitted intact– Trace evidence must NOT be removed from articles

(clothes, weapons, etc…)– Careful removal & packaging of evidence adhered to

objects

Dealing with Physical evidenceCollection & Packaging of Physical

Evidence

– If evidence on LARGE objects (doors, walls, etc…); remove with forceps

– Blood stain:• Scrape surface of stain• Use moist swab, for blood• Cut stained area out

– Different items or items (similar) at different locale MUST be put in separate containers

• Prevents damage & cross-contamination

Dealing with Physical evidenceTools of Evidence Collection

Various Tools/Equipment• Forceps

– collecting smaller evidence

• Plastic pill bottles – hairs, glass, fibers

• Manila envelopes, Screw-cap glass vials, cardboard pill boxes, or druggist-folded paper– MOST trace evidence

• Paper bags– Bloodstained materials (AIRTIGHT: mold may develop)

• Air-tight containers– Charred materials (prevent evaporation of accelerants)

Dealing with Physical evidenceMaintain the Chain of Custody

• Continuity of possession (Chain of Custody)– MUST be ESTABLISHED & MAINTAINED– Failure to keep an accurate Chain of Custody:

• Questions of authenticity/integrity

• ALL evidence packaged & marked, when retrieved at scene– Location, type, individuals (handling evidence), type of

analysis– Record kept of acquisitions/returns– Minimum handlers RECOMMENDED

Dealing with Physical evidenceObtain Standard/Reference Samples

• P.E. w/known origin (blood/hair sample from suspect)– For COMPARISON

• May be obtained from victim, suspect, or other known source– Ex: hairs (murder, etc.), paint samples (hit-and-run)

• Having a standard = improves success of investigation– Hair from a crime scene ONLY valuable, if there’s a reference– Buccal swabs (inner cheek swab) accompany bloodstain evidence [for DNA]

• Substrate controls (may be needed)– Untainted material close to area of evidence– Ensures that surface does NOT interfere w/tests {Arson, accelerants}

• Correct packaging of references/substrates - NECESSARY

Dealing with Physical evidenceSubmitting Evidence

• Submit in person or by mail– Determined by distance b/t submitting agency & lab; as well as

Urgency– Delivering individual should know about case– USPS restrictions: chemicals, explosives, live ammo

• MOST labs require Evidence Submission Form– Allows analyst to complete accurate exam– Include brief history of case– Logical sequence– Proper comparison

• Key Points to Note when evidence submitted– Search patterns– Items “found” ONLY through analysis– Placed in separate containers– Chain of custody maintained– Proper reference (standard) samples

The Murder Scene: Death & Autopsies

Role of Forensic Pathologist• MUST answer many basic questions– Who is the victim?– What injuries are present?– When did the injuries occur?– Why & how were injuries produced?

• Main role of medical examiner– Determine cause of death– If cause NOT easily determined; an autopsy is completed

• Suspicious or unexplained death• NOT ALWAYS WHAT IT APPEARS, AT FIRST

• Manner of Death (5 categories)– Natural, homicide, suicide, accident, undetermined

The Murder Scene: Death & Autopsies

Estimating Time of Death• Medical Examiner evaluates stage of decomposition >

ESTIMATE T.O.D.– Rigor MortisRigor Mortis

• Immediately after deathImmediately after death• Muscles relax, then become rigidMuscles relax, then become rigid• Appears in first 24 hrs. & disappears within 36 hrs.Appears in first 24 hrs. & disappears within 36 hrs.

– Livor MortisLivor Mortis• Blood pools in areas “closest” to ground [when heart stops]Blood pools in areas “closest” to ground [when heart stops]• Skin appears “dark purple/blue” in “pooled” areasSkin appears “dark purple/blue” in “pooled” areas• Starts from death for up to 12 hrs.Starts from death for up to 12 hrs.

– Algor MortisAlgor Mortis• Process of body “cooling”, after death > to room temp.Process of body “cooling”, after death > to room temp.• Heat loss affected by location, climate, body size, & clothingHeat loss affected by location, climate, body size, & clothing• After an hour, temperature falls 1-1 ½ After an hour, temperature falls 1-1 ½ F each hourF each hour• Amount of K within inner surface eye [estimate T.O.D.}Amount of K within inner surface eye [estimate T.O.D.}

The Murder Scene: Death & Autopsies

Forensic Anthropology: Skeletal Detectives• MAIN role = ID & examination of skeletal remains

– Breakdown/decay may take years; VERY DURABLE– Skeletal remains hold many INDIVIDUAL characteristics

• Analysis of bones MAY reveal age, race, & injury– Variations occur b/t the bones of men & women– Variations occur based on individuals age, too

• Facial reconstruction may be used to ID a victim or understand situation

• Anthropologists > ID victims in MASS accidents– Bone fragments CAN help in an ID

The Murder Scene: Death & Autopsies

Forensic Entomology: Testimony from Insects

• Study of insects & their relationship to criminal investigations

• MUST know: insects, their life cycles, & habits• 1st insects: blowflies

– Lay eggs– Maggots hatch & digest tissues/organs

Crime-Scene SafetyAids/hepatitis B and other diseases have led to more guidelines.

*Both transmitted through body fluids

No way to gauge health hazard possibilities

OSHA requires law enforcement officers to get hepatitis B vaccine {@ No charge}

Know IAISC guidelines {pg.49}

Legal Considerations @ the Crime Scene

“Inadmissibility” of evidence = exasperation and/or demoralization

* 4th amendment > Right to “privacy”= No search/seizure w/o warrant

Since 60’s > Supreme Court particular on searches w/o search warrant

1) Emergency situation

2) prevention of immediate loss of evidence

3) search of immediate person/property @ arrest

4) parties consent to search

Legal Considerations Cont. In 1978, addressed the issue of warrantless search & set guidelines.

* 2 cases: homicide & arson1) Mincey vs. Arizona > legality of 4 day search @ homicide scene

- uncover officer killed in scuffle @ drug raid - upheld conviction = emergency situation

2) Michigan vs. Tyler > business destroyed by fire- smoke, steam,darkness> limited search- unattended building ‘til 8 am- evidence removed/ 25 days later more evidence -court overturned ruling> subsequent searches were inadmissible

IF TIME/CIRCUMSTANCES PERMIT, GET A WARRANT

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