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Do Now: Observation v. Inference. Provide 5 observations and 5 Inferences. Chapter 2 “ One chance to work a crime scene... ONE.”. Eyewitness Testimony. Faulty eyewitness testimony contributed up to 87% of wrongful convictions. -1992 Innocence project. Observation v. Inference.

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Do Now: Observation v. Inference

Provide 5 observations and 5 Inferences

Chapter 2“One chance to work a crime scene... ONE.”

Eyewitness Testimony

  • Faulty eyewitness testimony contributed up to 87% of wrongful convictions.

-1992 Innocence project

Observation v. Inference

Provide 5 observations

Observation v. Inference

Provide 5 observations

How information is processed in the brain

  • Observations

  • Inferences

  • Perception is limited and the way we view




















What do you notice?

  • Transparency On

  • Perception video


Why can Perceptions of witnesses be faulty?

  • Perception is Subjective

    • Prejudicial

    • Emotional state

      • Upset/anxiety, happy or depressed

  • Fear at the time of stress

  • How humans are wired

Perception test video

Perception test video

Ugly to beauty video

How to be a good observer We know that we:

  • NOT inclined to pay attention to details

    • Make a conscious effort to examine systematically

  • Filter out unimportant material

    • Instead cat like data gathering machines

  • Jump to conclusions

    • We must make observations

  • Memories are faulty

    • Documentation is paramount,

      • Narrative, Photographs, Sketches


A. Processing the Crime scene:-What is a Crime Scene?

  • All areas over which the victim, criminal and eyewitness move during the commission of a crime.

  • Pathways to and from.

  • The physical location at which an offense was committed; to include lines of approach and flight.

  • The area of the crime scene can be relatively small or very large.

Events while approaching the scene

  • Securing and preserving the scene

  • Search and collection

What is the ultimate goal of the CSI team?

The goal of an investigator is to:

  • Recognize

  • Document

  • Collect evidence at the scene of a crime

Remember Locard’s Exchange Principle?

  • It is impossible for a perpetrator to commit a crime without leaving or taking something at or from the scene of a crime.

The Seven S’s of crime-scene investigation

  • Securing the scene

  • Separating the witnesses

  • Scanning the scene

  • Seeing the scene

  • Sketching the scene, (documenting)

  • Searching for evidence

  • Securing & Collecting evidence

Kurt Cobain

Facts about Kurt Cobain's death

  • Found April 8th 1994 dead in his home in Seattle Washington on the second story of his garage (green house)

  • Shotgun wound to the head.

    • face was still intact contrary to popular belief

    • 3 times the lethal dose of heroin in his blood stream

    • no finger prints on the gun, suicide note, or shell casing [as if they had bin wiped clean]


Tom Grant's sketch of the scene

Objective: Identify The Seven S’s of crime-scene investigation found within your narrative

Securing the scene

Separating the witnesses

Scanning the scene

Seeing the scene

Sketching the scene

Searching for evidence

Securing & Collecting evidence

Anything wrong in the excerpt from the Follow Up Report?

  • Obvious trauma to his head. There is a Remington m-11 20 gauge shotgun between the victim’s legs with the barrel pointed towards his head and his left hand wrapped around the barrel. The shotgun is inverted with the trigger and magazine trap door pointing up. The barrel end is just above his beltline. There is a sent 20 gauge shell casing on top of a brown corduroy jacket which is on top of a beige nylon shotgun case. These are just to the left of the victim and under one of the stainless steel garden trays.

Excerpt from the Follow Up Report

Remington m-11 20 gauge shotgun

  • The inverted shotgun distinguishing the orientation that relates to the scene diagram

  • Total length 45 in

Greenhouse door

Inside the Greenhouse

  • The stool police claim Kurt used to "barricade" himself in the room

  • greenhouse lock used to back up the story that Kurt "barricaded" himself in the Greenhouse

Suicide Note


üCollection of physical evidence

  • -record Chain of Custody

    üEstablish that a crime has been committed (corpus delicti _ elements of the crime)

    üReconstruction of the crime

    üIdentification / Link suspect to the crime scene

    üEstablish probable cause

Physical Evidence

  • Any object that can establish a crime has been committed

  • can provide a link between a crime and its victim or

  • between a crime and it’s perpetrator

    • Direct vs. circumstantial

    • Physical vs. biological

    • Class vs. Individual

      • Trace

Comparison:Two types of characteristics

  • Class characteristics:

    • Substances can be associated with a group but not individual source

    • Blood types: use factors in blood

    • These can ID suspects at a crime scene

  • Individual characteristics:

    • Substances that are related at almost 100% probability

    • Fingerprints are 1x1060 that 2 peoples are the same

The Crime Scene Investigation team

  • Police officers: first arrival, DA if warrant was needed

  • CSi: document the scene +collect evidence,

    • recorders for: photograph, narrative, sketch

    • Evidence collectors

  • Medical examiner/ coroner

    • Detectives: interview witnesses

  • Specialists: specialized forensic specialists

    • Entomology, serology, anthropology

Secure and Isolate the Crime Scene

  • There are three phases of crime scene management.

    • Initial Notification and Response Securing,

    • Searching the crime Scene and Documenting

    • Disposition

      These three phases can be identified in 16 basic steps.

Crime scene search case law


    • Ability to identify each item of evidence

    • Describe exact location of evidence

    • Reconstruct crime scene

    • Maintain chain of custody

    • Explain any changes that might have occurred between the collection and preservation of the evidence.

Objective: Role Responsibilities

Please assign a minimum of three Responsibilities to each member your team.

  • 1st Officer (+facilitator)

  • Recorder

  • Photographer

  • Sketch Artist

  • Narrative

  • Evidence Collectors

“The Bone Collector”

If at anytime you feel threatened or uncomfortable,

feel free to close your eyes!

If you feel this approach will not work not you, you may sit in the hallway,

Absolutely ALL alone where the murder may still be!

2. Record the scene

  • The opportunity to permanently record the scene in it’s original state must not be lost.

    • Photography

    • Sketches

    • Notes

Record the scene: Photography

  • Conducted before anything else is done to the crime scene.

  • Crime scene photographs can:

    • Refresh the memories of investigators and witnesses

    • Provide powerful evidence to a jury

  • Details positions and locations of evidence

  • The crime scene and all physical evidence should be photographed from all angles.

  • Videotaping of the crime scene is acceptable, not a replacement for 35mm

  • Record the scene: Photography

    • Cardinal Rules of Photography

    • 1. Nothing moves until it is photographed!

    • 2. Film is cheap -- you can't take too many crime scene photographs.

    • Once the scene has been photographed, the investigator will need to sketch the crime

    Record the scene: Sketches

    • The Four Keys to Crime Scene Sketch

      • 1. Dimension

      • 2. Distance

      • 3. Context

      • 4. Relationship Among Items of Evidence

    • * Record the exact location and relationship of pieces of evidence to surroundings.

    • * Refresh the memory of the investigator.

    • * Provide permanent record of conditions not easily recorded.

    • * Assist prosecutor, judge, and jury to understand conditions at the crime scene.

    • * Help in questioning suspects and witness.

    • * Plan raids and roadblocks.

    • * Help correlate testimony of witnesses.

    • * Eliminate unnecessary and confusing details.

    Purposes of Sketch

    Record the scene: Rough Sketches

    Record the scene: Final Sketches

    Systematic searches

    • Need to be done so that no accusations of a cover up arise or overlook of evidence

    • Need one person in control to coordinate collection of evidence

    • Four main types

      • Spiral

      • Strip or Line

      • Grid

      • quadrant

    Four main types

    • Spiral

    • Strip or Line

    • Grid

    • quadrant

    Four main types

    • Spiral

    • Strip or Line

    • Grid

    • quadrant

    Mobile crime scene laboratories

    • Protect the scene, photograph, evidence collection and packaging, latent fingerprinting.

    • Microscopic or Undetectable at the scene

    • Ex. Hair, blood, fibers from clothes, Fabric impressions, traces of paint

    • DO NOT carry out the functions of a chemical lab

      • Crime scene search vehicles

    Vacuum Sweeping

    • Critical areas of a crime scenes should be vacuumed and swept.

      *Looking for traces evidence.

    Collect and Package Physical Evidence

    • Crime scene safety ALWAYS a concern!

      • Hepatitis, HIV, AIDS, Bio-hazardous pathogens

    • Use forceps, doubled gloves, tyvek or kleengard type suits


      • The chain of custody

      • A record denoting the location

        of the evidence

    Maintain Chain of Custody

    • A list of all persons who came into possession of an item of evidence.

      • List provides:

        • Date

        • Location of evidence

        • Id #

        • Collectors initials

        • Persons who handled or examined

    Collect and Package Physical Evidence

    • Must be handled and processed in a way that prevents ANY change, between the time it is removed and the time it is received by the crime scene lab.

      • Contamination, breakage, evaporation, scratching, bending, LOSS

    • Evidence should be collected intact

    Collect and Package Physical Evidence

    • Must be organized:

      • Packaged separately in:

        • Plastic pill bottles

        • Manila envelopes

        • Screw top glass vials

        • Cardboard

          Mailing envelopes not recommended

    Do Now 9/30:

    Please have ready your crime scene reports

    Obtain Standards/Reference Samples

    • Standards/reference: Physical evidence whose origin is known, blood, hair, DNA

    • Buccal Swab: swab of inner portion of cheek, for cheek cells DNA profile or blood

    • Substrate Control: uncontaminated surface material close to an area where physical evidence has been deposited.

    Obtain Standards/Reference Samples

    • DNA profile

    Crime Scene Admissibility

    • Michigan v. Clifford

    • Michigan v. Tyler

    • Mincey v. Arizona

    Crime Scene Admissibility

    • Michigan v. Clifford -

      Investigators searched an arson fire scene five hours after the fire was put out, without

      consent or warrant. Incriminating evidence was recovered and used in the conviction.

      The US Supreme Court reversed the decision citing the need for a warrant five hours

      after the fire was put out.

    Crime Scene Admissibility

    • Michigan v. Tyler -

      Arson investigators conducted three separate searches of a fire scene. The first was one

      and one-half hours after the fire, but dense smoke caused the search to wait until four

      hours later (the second search). The third search was weeks later. Evidence from the first

      two searches was held admissible, but evidence from the third search was excluded.

    Crime Scene Admissibility

    Mincey v. Arizona –

    investigating the shooting death of an undercover police officer in the residence of the suspect.

    * The police established a crime scene, conducted a thorough search of the scene and found evidence of other crimes.

    ** The police charged the suspect with those crimes as well and the court rejected it.

    *** The court recognized the need of the police to control the situation upon their arrival, and the need to establish a crime scene. But as soon as there was no more danger of evidence loss, removal or destruction, there was ample time to obtain a search warrant, particularly when evidence of other crimes was inadvertently discovered.

    What is a Crime Scene?

    What is a Crime Scene?

    What is a Crime Scene?

    What is a Crime Scene?

    • Lack of evidence IS evidence.

      • No scratches on the arms, defense wounds, could be evidence of suicide.

      • Must prove intent, to prove suicide.


    Pictures page

    Major stages in crime scene processing, (Initial and response)

    1) Receive call and make initial response

    2) Make careful approach to crime some

    3) Establish control/jurisdiction

    Major stages in crime scene processing, (Initial and response)

    1) Receive call and make initial response

    2) Make careful approach to crime some

    3) Establish control/jurisdiction

    16 STEPS (Secure, Document and Search)

    4) Secure and protect, 1st officer

    5) Establish/confirm crime scene perimeter, assisted by multiple officers

    6) Conduct preliminary survey

    7) Write narrative description

    8) Photograph crime scene

    9) Sketch crime scene

    6) Conduct preliminary survey**

    • First responding investigator should note:

      • Who made the notification?

      • What time did the 1st officer arrive

      • How long did that take? “arrival lag”

      • Weather conditions, visibility

      • Persons on scene, at, left, or passed through

      • Who facts ascertained by first officers

      • Observations of “key items of evidence”

      • Takes responsibility form officers from the scene

    16 STEPS (Secure, Document and Search)

    10) Evaluate for latent impressions

    11) Evaluate physical evidence

    12) Conduct detailed examination

    13) Collect, record, mark, and preserve evidence

    14) Conduct final survey of scene

    15) Review documentation and process

    16 STEPS IN CRIME SCENE PROCESS, (disposition)

    16) Release and/or secure the scene

















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