1) The rough sketch
- the rudimentary first sketch created at the crime scene with care for accuracy in depicting
dimensions and locations but no concern for aesthetic appearance.
- required tools: graph/drawing paper, 2 measuring tapes, clipboard/drawing surface, pencils,
straightedge ruler, erasers, compass/GPS device, optional tools: drawing compass, protractors
architect scales, French curves, drafting triangles, rolling measurement devices
- all sketches must include the following features
- title block with case #, agency #, name/title of artist, location of scene, date, time,
victim's name, name of suspects, type of crime
- must appear in lower right hand corner
- legend which contains the key to identity and dimensions of objects or evidence
may be represented by symbols, letters or numbers
- compass that includes an arrow that determines North in relation to the scene
- body of the sketch contains the drawing itself and all dimensions and objects
located within it
Example of a rough sketch:
2) Creating the sketch
A) Define the boundaries of the sketch. These may be walls for an indoor sketch. Make sure
that the area within these boundaries includes all the pertinent objects and evidence.
B) Establish known points from which to measure the locations of objects and evidence.
These points should be fixed. These can be walls or doors in indoor scenes. Trees,
telephone poles, street signs, or natural features (i.e. boulders) can be used for outdoor
scenes.
C) The walls or boundaries should be drawn first, leaving as much room as possible for the
contents. If walls are used, their dimensions should be recorded.
D) Measurements should be taken from the fixed points to pieces of evidence first. There are
3 methods of measurement from the two points of reference.
- rectangular method measures two distances to an object that make a
right angle with each other and to two fixed, flat surfaces. These
surfaces are usually walls
- triangulation method measures the distance of the object from two
fixed points of known distance from each other. This makes a triangle
In an indoor scene, these points are usually the corners of a room.
- baseline method is especially useful for outdoor scenes. First, two
fixed objects on opposite sides of the scene are located. A line is
then made between them and measured. Each object or piece of
evidence has a line from it to the baseline to make a 90 degree angle
with the baseline. The distance of the line from the object to the
baseline is then measured, along with the point of intersection with
the baseline.
- polar coordinates method uses only one reference point. The sketch
should show the distance and angle at which an object is located in
the scene relative to the reference point.
3) The Finished Sketch
- The perfected final sketch that is constructed with care and concern for aesthetic appearance
and drawn to scale
- legend must contain the scale
- must reflect information contained within the rough sketch to be admissible evidence in court
- indoor sketch shows the floor of one or more rooms, doors and windows, and any
evidence or objects on the floor
- outdoor sketch shows almost an aerial view of the small or outdoor scene
- can be done by a hired professional, by hand in pen or by computer (with CAD)
Here are some sketches: Two are final sketches
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