1. CRIME SCENE SKETCHING PURPOSE
TO PROVIDE 3 DIMENTIONAL REPRESENTATION OF SCENE
TO PROVIDE SELECTIVE VIEWS
TO SUPPLEMENT PHOTOGRAPHS

2. TYPES OF SKETCHES
ROUGH SKETCH
FINISHED DRAWING

3. ROUGH SKETCH Accurate depiction of dimensions of scene
Location of all objects having a bearing on case
Objects located from fixed point
Measurements made with tape measure
Use legend to locate items
Show compass heading

4. ROUGH SKETCH Importance of rough sketch
It enables an officer to obtain a lasting picture of the crime scene which will assist him to review the circumstances of the incident after the original scene has been changed or destroyed

5. ROUGH SKETCH Importance of rough sketch
The sketch helps a witness to recall some particular facts. It permits him to clarify statements by indicating his position when he observed the event, the location of the principals and of certain objects at the time of the occurrence.

6. FINISHED SKETCH Drawn for Aesthetic appearance
Use templates and drafting tools
Drawn to scale
Must reflect evidence in rough sketch
CAD programs now available

7. FINISHED SKETCH Value of Finished Drawing
Helps the Judge and Jury to obtain a better understanding of the scene and the testimony of the investigator and witnesses
Case presentation strengthened by accurate and professional drawing which creates a favorable impression with the jury. Instills a respect for the efforts and ability of the police to present the facts

8. INFORMATION ON SKETCH Case identifying information Scale
Case number, investigator,date, time
Scale
Distance measurements
Reference points
Legend to identify portions of drawing

9. EQUIPMENT FOR SKETCHING
Pens or pencils (Pencils better)
Colored pencils
Graph paper
Drawing surface (clipboard)
Measuring devices (rulers or tapes)
Compass

10. Type of sketches Bird’s-eye view Elevation Drawing
Items located in one plane
Simple to draw
Easy to understand
Elevation Drawing
Vertical plane of interest (wall)

11. Types of sketches Cross-projection (exploded) view Perspective drawing
Combination of bird’s-eye and elevation
Similar to bird’s-eye
Walls folded down into same plane as floor
Perspective drawing
Three dimensional drawing
Requires considerable skill
Not generally recommended

12. LOCATING OBJECTS Actual position in the scene where object located
Position defined by two measurements
Perpendicular measurements easier
Must use fixed points to locate objects
Must be permanent and identifiable
GPS may become useful in future

13. MEASUREMENTS All measurements must be accurate
Distances never paced off
All measurements taken with measuring device and verified by second officer if possible
Moveable objects not used as point of reference, only fixed objects

14. MEASUREMENTS Basic methods of obtaining measurements
Rectangular coordinates
Straight line measurements
Triangulation

15. MEASUREMENTS Rectangular coordinates
Useful in sketching indoor crime scenes
Two measurements are made at right angles of an item to the nearest two permanent objects (usually walls)

16. Rectangular coordinates

17. STRAIGHT LINE MEASUREMENTS
Usually made of furniture or evidence on a wall
Two measurements are taken, one from each side of the object

18. Straight line measurements

19. TRIANGULATION May be used indoors or outdoors
Two fixed points are selected as points of reference
Measurements taken from the object to each point forming a triangle

20. Triangulation

21. RULES FOR ROUGH SKETCH Decide what is to be sketched
Determine compass direction
Control all measurements
Have another officer verify measurements
Don’t estimate distances by pacing

22. RULES Use a measuring tape or rule – be accurate
Locate all objects accurately
Include all essential items – exclude the irrelevant
All corrections must be made at scene

23. RULES
When locating a body use two measurements, one to head one to feet
All bodies shown as stick figures
All objects identified either with letters or numerals
All objects described in detail in notes

27. ADMISSIBILITY OF SKETCHES
Must be entered by someone competent to testify about authentiity
Must testify that it is true and accurate representation of scene