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AJ 104. Crime Scene Evidence, Experiments, and Models. Freeze!!!. Introduction. Real Evidence Anything that can be perceived with the five senses, except, trial testimony. Real Evidence Must be marked and formally introduced into evidence

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aj 104

AJ 104

Crime Scene Evidence, Experiments, and Models

  • Real Evidence
    • Anything that can be perceived with the five senses, except, trial testimony.
  • Real Evidence
    • Must be marked and formally introduced into evidence
    • The attorney who wishes to introduce them must lay a foundation to establish the admissibility of the items in question.
real evidence includes
Real Evidence Includes:
  • Physical items
    • Guns, Knives
  • Documents
    • Will be covered in the next chapter
  • Exhibits
    • Models, renderings to depict a crime scene
  • Pictures
    • Still, video, x-rays
introduce evidence in 4 easy steps s a f f
Introduce Evidence In 4 Easy Steps (S.A.F.F.)
  • Show evidence to defense to examine (if desired)
  • Assign a number (the court clerk mark the evidence as People’s No. #)
  • Foundation is laid to establish the item is admissible.
  • Formal request is made to admit it into.

pg. 125

crime scene evidence
Crime Scene Evidence
  • Items admitted must be authenticated
    • To show that an item is genuine
    • To show is the same one described by the witness
    • The item needs to be the same condition as it was found by the police unless tested
    • Careful handling of evidence and accurate report writing are crucial
    • WHY?
at the crime scene
At the Crime Scene
  • Protect the evidence
  • Restrict public access
  • Do not clean the area
  • Always better to have too many than not enough
  • Save everything of evidentiary value
  • WHY?
laying the foundation
Laying the Foundation
  • The series of questions an attorney asks witnesses in order to establish that a piece of evidence is admissible
    • Have someone identify the object and testify about where the item was found
    • What has been done since it was taken into the custody?
    • WHY?
marking packing sketching
Marking & Packing, & Sketching
  • Once an object is identified and can be used as evidence, it should be marked at the time it is collected
    • Before collecting and packaging , make a detailed recordation of the crime scene/collection
    • Mark with the officer’s initial’s
    • They should not be placed where they may interfere with lab results
    • Exercise caution preserve fingerprints, blood, DNA, etc.
marking packing sketching1
Marking & Packing, & Sketching
  • When possible, try to do as many f the following as possible:
  • Make sketches of the location (to scale) indicating where the object was found
    • Locations of doors, windows,
  • Take photos of the area
  • Make detailed notes
The proper packaging of evidence is extremely important
    • Evidence needs to be preserved for trial
    • Care must be taken not to damage, evaporate or contaminate
    • Each piece of evidence must be packaged individually & labeled on the outside.
    • Leave enough space for everyone who handles the evidence will indicate the date, time, and reason for handling it.
Chain of Custody
    • Also called “continuity of possession”
    • It is necessary to account for everyone who has had possession of the evidence in order to show the judge and jury that the evidence has not been tampered with.
    • Pg. 129 (sketch)
scientific evidence
Scientific Evidence
  • Forensics
    • Can be used to established the elements of the crime
    • Conclusively associate the defendant with the crime,
    • Help reconstruct the crime
types of cases using scientific evidence
Types of Cases Using Scientific Evidence
  • Police are likely to clear a case when scientific evidence is used.
  • Jurors give scientific evidence serious consideration, but is not the key element
  • 2/3 of their cases involve:
    • Drugs
    • Narcotics
    • Drunk Driving
types of cases using scientific evidence1
Types of Cases Using Scientific Evidence
  • The next most common categories were:
    • Firearms
    • Blood & Bloodstains
    • Semen
  • Forensic evidence was used in nearly all murder and drug possession cases.
scientific evidence laying the foundation
Scientific Evidence, Laying the Foundation
  • The foundation for the introduction of scientific investigation involves answering three questions:
    • Is this a valid scientific test?
    • Was accurate equipment used for the test?
    • Was this test performed in an appropriate manner by a qualified person?
  • Both sides will call their expert witnesses to challenge the validity of the test.
commonly accepted scientific tests
Commonly Accepted Scientific Tests
  • Many tests are so well established that they are admitted at trial without a challenge to their validity.
    • Identification of Controlled Substances
    • Identification of Firearms
    • Blood Alcohol
    • Blood Typing
    • DNA Testing
tests not commonly accepted
Tests Not Commonly Accepted
  • Scientific tests must be accepted in their field before the courts are willing to allow their use at trial
    • Polygraph
      • The high frequency of inconclusive results makes the courts distrust the results of a polygraph
    • Hypnosis
      • It is still a concern of the court being in a trancelike state and being unconsciously responsive.
  • Screens out all extraneous variables so that the experimenter ca measure the impact of one factor.
    • Few experiments are introduced in court