Unit 1:Crime Scene Basics

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Allen Franklin
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1 Unit 1:Crime Scene Basics

2 1904 Edmond Locard The Locard Exchange Principle: Whenever two objects come into contact with one another, a traceable exchange is made.

3 Evidence Physical Evidence: Any object that can establish a crime has been committed or can link a crime and its victim or its perpetrator. Typically found at the crime scene.

4 Common Types of Physical Evidence Drugs/Poisons Paints Gunshot Residue Firearms/ammunition Impressions (shoe, bite etc) Petroleum Products (gas residue, oil etc) Alcohols (ethanol when drinking is involved.) Plastics, rubber, polymers Explosive residues Serial Numbers Documents Fibers Soil Glass Blood Body Fluids Fingerprints Hair Tissues Wood Materials Feathers Bones Tool Marks Powder Residues Hair

5 Categories of Physical Evidence Individual Evidence: Evidence that can be linked to a unique, single source. Class Evidence: Most common. Evidence that has characteristics of a group. (not specific)

6 Federal Rules of Evidence The Frye Standard: Called the general acceptance test. Mandates that scientific evidence is only allowed in court if the science methods/theories that it is based on are generally accepted by the scientific community.

7 Federal Rules of Evidence The Daubert Ruling Updated version of the Frye Standard Occurred because of the changing nature of science (advancements) reading. Judges must now ask themselves if the evidence being presented follows the scientific method (it can be repeated, error analysis is sound, etc.)

8 Processing the crime scene. Oh, how simple it would have been had I been here before they came like a heard of buffalo and wallowed all over it. ~Conan Doyle.

9 Securing the crime scene Securing the scene means preventing any damage to the scene. The first officer arriving is responsible for securing the scene. To secure it officers will use ropes, crime tape, barricades and sometimes guards.

The first officer arriving is responsible for securing the

10 Securing the scene. Step 1: Determining the boundaries of the scene. Was it in more than one place? Was the body moved? Whole house? Undetermined?

11 Securing the scene. Step 2 Determine the perpetrator s path of entry or exit. What would you look for?

12 Securing the scene. If there was a death the medical examiner will identify the bodies condition and estimate the TOD

13 Securing the Scene Step 4: First sketch the scene, take pictures. Begin collecting physical evidence.

14 Securing the Scene Step 5: Investigator interviews witnesses and first responder.

15 Photography A photo lasts forever!! He or she should give special attention to: points of entry or exit Where evidence is placed View scene through the eyes of a witness. Any other pictures that will help the jury visualize the scene. Should include a ruler for scale. Avoid scrapbook-type photos or poses by officers on the scene.

evidence is placed View scene through the eyes of a witness.

16 Photography

17 Sketching Sketches are helpful because they provide a permanent record of points of interest in reference to each other. They allow for selectivity. You can leave out or add things that you deam nescessary. They give measurement and scales. Must include date, time, scale, reference points (N,S,E,W), distances, name of investigators, victims, suspects, and a legend. Once completed it can not be changed it is treated as evidence.

18 What do you Sketch? Record size of entire scene. Record weapon(s) Record bodies/victim location Record entry/exits Record furniture Record blood spatter patters/location Record smashed, tipped over items indicating a struggle. Record proximity of objects GENERAL: RECORD ANY KEY INFORMATION!

furniture Record blood spatter patters/location Record smashed, tipped

19 Triangulation Method All objects are measured from 2 FIXED points. Use right angles.

21 Final Sketch This is not done at the scene. Often uses computer drafting programs, such as CAD. Done in pen (if not using the computer). Must use a ruler. Precision limited to rough sketch you cannot add items or change the scale. Must be included as evidence. Often enlarged to a poster-size image for trials.

22 Final Sketch

23 Chain of Custody Chain of Custody is a written record of who had possession of every piece of evidence at all times. This record appears directly on the package itself. This is partly what OJ Simpson s attorney s argues was a problem with his case.

Goal to recognize, document and collect evidence at a crime scene

Crime Scene Investigation and Evidence Collection Lecture Credits: Anthony (Bud) Bertino Goal to recognize, document and collect evidence at a crime scene Sherlock Holmes» Sir Arthur Conan Doyle in the