Post on 19-Jan-2016
description
Observations vs. Inferences
Chapter Goal & Assessment
• To demonstrate the following skills in the processing of a crime scene
1. Securing the crime scene
2. Documenting the scene
3. Collecting & packaging evidence
Unit 2: THE CRIME SCENE
“Oh, how simple it would all have been had I been here before they came like a herd of buffalo and wallowed all over it.”
—A. Conan Doyle, in The Boscombe
Valley Mystery, 1892
CRIME SCENE
You will learn: The steps to take when
processing a crime scene. That type of evidence
determines what packaging should be used.
Why the chain of custody must be preserved.
You will be able to: Isolate, record, and search for
evidence at a mock crime scene.
Collect and package evidence at a mock crime scene using to proper forensic procedures.
CRIME SCENE TEAM
A group of professional investigators, each trained in a variety of special disciplines.
Team Members First Police Officer on the scene Medics (if necessary) Investigator(s) Medical Examiner (if necessary) Photographer and/or Field Evidence Technician Lab Experts
PROCESSING ACRIME SCENE
Isolate and secure the scene
Record/Document the scene
Collect and package evidence, maintaining the chain of custody
Submit evidence to the crime lab
Overview of Duties
FIRST OFFICERON THE SCENE
• Assist those hurt: may destroy evidence, but saving someone takes priority
• Assess the crime scene: give consideration to offenders approach and flight path
• Detain the witness(s)
• Protect the crime scene: establish a boundary that is too large, then collapse it later. Limit access (even to other officers) and create log of people on the scene
• Take notes: more on this later…
• Make appropriate notifications: ME, CSIs,
Investigators
CRIME SCENE SURVEYperformed by the CSI
Interview the first responding officer to find out details Determine what is usable and relevant evidence (experience helps with
this) Observations:
Walk through to develop a mental plan of how the scene should be handled Oblique lighting: technique used indoors to reveal items not visible under
ordinary light Documentation & Recording duties:
Notes Photographs/Video Sketches
Search, Collect, and Package evidence
SEARCH METHODS
One person should be responsible for supervising collection of evidence
Line or strip method—best in large, outdoor scenes Grid method—basically a double-line search; effective,
but time-consuming Zone method—most effective in houses or buildings;
teams are assigned small zones for searching Wheel or ray method—best on small, circular crime
scenes Spiral method—may move inward or outward; best used
where there are no physical barriers
DOCUMENTATION
Notes extremely important, forces observation Weeks, months, years later Should Include:
date and time, description of the location, weather and environmental conditions, description of the crime, location of the evidence relative to other key points, the names of all people involved, modifications that have occurred and other relevant information
CRIME SCENE SKETCH
*** Review the supplemental handout on Sketching ***
Importance of the crime scene sketchImportance of the crime scene sketch
•compliments the photographs by giving spatial relationships
•Communicates information that words cannot describe
•Can be drawn to selectively include only relevant material (confusing detail can be eliminated)
•Better overall depiction of the scene
•Easy to show travel routes of suspects, victims and vehicles
CRIME SCENE SKETCH
Date: August 14, 2005 Criminalist: Ann WilsonTime: 11:35 am Location: 4358 Rockledge Dr, St. Louis, Mo.
N
*** Review the supplemental handout on Sketching ***
CRIME SCENE SKETCH
*** Review the supplemental handout on Sketching ***
Types of Crime Scene SketchesTypes of Crime Scene Sketches
Baseline – useful outside or in area with aisles
Rectangular Coordinate – easiest and most common
Triangulation – 2 fixed points and form a triangle
Polar Coordinate – very difficult
We will learn to use …. Baseline and Rectangular Coordinate
CRIME SCENE SKETCH
*** Review the supplemental handout on Sketching ***
Sketching on the SceneSketching on the Scene
Important:
Rough vs. Clean
Get all you information and details…do not worry about it being pretty…you can clean it up when you get back to the office!
DOCUMENTATION
Notes—date and time, description of the location, weather and environmental conditions, description of the crime, location of the evidence relative to other key points, the names of all people involved, modifications that have occurred and other relevant information
Photography—photos of scene and surroundings, far, mid-range to close-up photos with 90 degree and various angles of each piece of evidence, photos as viewed by any witnesses.
Sketches—inclusion of date, time, scale, reference points, distance measurements, names of investigators, victims, suspects, and a legend (key)
Evidence Collection - packaged, marked, sealed, and preserved in a consistent manner
Videography—allows narration (non-subjective) to be included
ROUGH SKETCH TO FINAL SKETCH
This is what I made at the scene.
This is what I made at the office.
ROUGH SKETCH TO FINAL SKETCH
Put your measurements on your sketch
Use two perpendicular surfaces to make your measurements.Usually these are two walls
Use a method to indicate which direction the measurements are made
10 ‘ S and 7 ‘ E
10 ‘ X 7 ‘ Y
10 ‘ 7 ’
Rectangular Coordinate Sketching Method
Baseline Sketching Method
Pick a reference point
Make a straight reference line
Make 90 degree measurements from the reference line showing direction
Baseline Sketching Method
Cumulative vs. Consecutive Measurements
Cumulative method
anchor the tape at one end and measure all the points from that reference point Less likely to result in an error
Consecutive method
measures from one point to the next point and so on…with this method if you have an incorrect measurement the others are wrong too*****DO NOT USE *****