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CRIME SCENES, EVIDENCE & CRIME SCENES, EVIDENCE & FORENSICSFORENSICS

LEARNING DOMAIN 30

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GOAL OF A CRIMINAL INVESTIGATIONGOAL OF A CRIMINAL INVESTIGATION

An investigation is the systematic gathering of information from a variety of sources and the documentation of evidence, observations and findings.

A criminal investigation is a systematic approach to the: establishment of a criminal violation identification and arrest of a suspect, and gathering of evidence for presentation in a court of law

REMEMBER:REMEMBER: the goal of any criminal investigation is the successful prosecution of the guilty and exoneration of the innocent

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PRELIMINARY INVESTIGATIONSPRELIMINARY INVESTIGATIONS

The preliminary investigationpreliminary investigation begins when the responding officers first arrive at the scene of the incident. It continues through the writing and filing of the primary officer’s investigation report (w/b p. 3-4)

“the evidence never lies”Horatio Caine

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COMPONENTS OF THE COMPONENTS OF THE PRELIMINARY INVESTIGATIONPRELIMINARY INVESTIGATION

1) Arrival: (w/b p. 3-5) proceed safely to the scene

2) Assessment: Determine need for emergency medical services Verify that a crime has occurred Identify and arrest suspect(s) if appropriate Provide dispatch with pertinent info ASAP

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COMPONENTS OF COMPONENTS OF PRELIMINARY INVESTIGATIONPRELIMINARY INVESTIGATION

3) Preliminary Investigation- Secure and protect the crime scene Identify and preserve possible evidence Locate and interview

victim(s)/witness(es) Identify other possible sources of info

4) Report- Collect available info necessary to write a

clear and effective investigative report

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CRIME SCENE PROTECTION CRIME SCENE PROTECTION CONSIDERATIONSCONSIDERATIONS

Establish an inner and outer perimeter Assign personnel to maintain

perimeters Place fixed barriers to maintain

integrity of the scene Maintain a crime scene log If necessary, take additional action to

protect the crime scene and physical evidence

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CRIME SCENE SURVEYCRIME SCENE SURVEY

Initial survey - Identifies the kinds and amounts of evidence that may exist at the crime scene. Purpose gives officers an opportunity to access, time, equipment, personnel needed to process the crime scene.

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CRIME SCENE SEARCHCRIME SCENE SEARCH Systematic, coordinated effort conducted in order

to: w/b p. 3-141. Locate physical evidence that a crime has taken place.

2. Identifies individual (s) who may have committed the crime.

Search patterns: choice based on type of crime, size of crime scene, number of personnel available, personal choice.

a) Line

b) Quadrant

c) Grid

d) Spiral

e) Wheel

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ADMISSIBILITY OF PHOTOGRAPHSADMISSIBILITY OF PHOTOGRAPHS Admissible as evidence if

they: (w/b p 3-17)1. Show an object or person

relevant to the crime2. Accurately represent,

without distortion, the object or scene photographed

3. Are marked properly to identify contents and location

4. Are not used solely for the purpose to appeal to the emotions or prejudice the court or jury

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BASIC SURVEY METHODSBASIC SURVEY METHODS

Rectangular – Identifies location of an object by it’s distance from two perpendicular lines.

Triangulation – objects located by determining where two or more lines intersect (useful out doors).

Coordinate/transect – use when the item of evidence lies somewhere along a straight line that has identifiable end points.

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COLLECTION OF EVIDENCECOLLECTION OF EVIDENCE

Prior to collecting, should consider: Photographing evidence to demonstrate

appearance when found. Diagramming the location and position of items of

evidence to aid in later reconstruction of the scene. Taking notes regarding the physical appearance of

evidence to document condition in which it was found.

Wearing appropriate clothing for the type of crime scene you are working.

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HANDLING EVIDENCEHANDLING EVIDENCE At risk evidence – that which can be lost,

damaged or contaminated:Fingerprints, biological fluids, stainsGunshot residue, paint chips, hairs &

fibers, flammable liquids & accelerantsShoe, foot, tire impressions

Trace Evidence – very small not seen with the naked eye

Transfer Evidence – easily transferred between two objects, i.e. paint chips, hair, fibers, soil, etc.

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PHOTOGRAPHSPHOTOGRAPHS Crime Scene Photos:

Provide visual record of crime scene Allows court to visualize scene & position of

evidence Preserves location

of fragile evidence Can be stored

indefinitely Show object or person

relevant to the crime Accurately represent the object or scene Marked properly to identify contents &

location

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PHOTOGRAPHSPHOTOGRAPHS

General Guidelines: Keep a detailed log Take photos prior to conducting a search Take numerous photos from different angles Use markers & scale measures in photos Use a tripod when available Identify photo taker, time & date, location

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EVIDENCE PACKAGING EVIDENCE PACKAGING CONTAINERSCONTAINERS

Paper – most dry items Cardboard – firearms/knives, dried blood

items, that need protection Metal – chemicals, flammable fluids/items Glass – items not compatible with metal,

materials with dried biological fluids Plastic – paper, small amounts of processed

narcotics

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CHAIN OF CUSTODYCHAIN OF CUSTODY The complete and accurate record of

evidence from crime scene to courtroom Property form formats should include the

following: (w/b p 3-25)1) Report number 2) Who initially found the item3) Where and when item found 4) Item description5) Who recovered, packaged, and labeled the item 6) Who transported 7) Where submitted8) Where, how, and when item was secured

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FORMS OF FINGERPRINTS EVIDENCEFORMS OF FINGERPRINTS EVIDENCE

FingerprintsFingerprints: : are a copy or impression of ridges and valleys present on the outermost layer of human skin on fingers. Also found on palms, feet and toes.

Visible – impressions in blood, paint, grease, etc

Plastic – impressions left on soft substance such as heavy grease, melted candle wax, putty, etc

Latent – impressions left by secretions from perspirations or oils on the skin (normally invisible to the naked eye until developed)

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