Observations vs. Inferences

1. Observations vs. Inferences

2. Chapter Goal & Assessment • To demonstrate the following skills in the processing of a crime scene • Securing the crime scene • Documenting the scene • Collecting & packaging evidence

3. 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 TheBoscombe Valley Mystery, 1892

4. 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.

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

11. CRIME SCENE SKETCH Importance 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 *** Review the supplemental handout on Sketching ***

12. CRIME SCENE SKETCH Date: August 14, 2005 Criminalist: Ann Wilson Time: 11:35 am Location: 4358 Rockledge Dr, St. Louis, Mo. N *** Review the supplemental handout on Sketching ***

13. CRIME SCENE SKETCH Types 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 *** Review the supplemental handout on Sketching ***

14. CRIME SCENE SKETCH Sketching 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! *** Review the supplemental handout on Sketching ***

15. 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

16. ROUGH SKETCH TO FINAL SKETCH This is what I made at the scene. This is what I made at the office.

17. ROUGH SKETCH TO FINAL SKETCH Put your measurements on your sketch

18. Rectangular Coordinate Sketching Method 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 ’

19. Baseline Sketching Method Pick a reference point Make a straight reference line Make 90 degree measurements from the reference line showing direction

20. Baseline Sketching Method Cumulative vs. Consecutive Measurements 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 ***** Cumulative method anchor the tape at one end and measure all the points from that reference point Less likely to result in an error