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

TYPES OF SKETCHES ROUGH SKETCH FINISHED DRAWING

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

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

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.

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

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

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

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

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)

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

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

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

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

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)

Rectangular coordinates

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

Straight line measurements

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

Triangulation

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

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

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

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