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Incident Scene Field Sketches
While a picture may be worth a thousand words an equally valuable
piece of evidence is the incident scene field sketch. It's exactly
what the name suggests, a free hand sketch drawn at the incident
scene. Its purpose is to portray the physical facts at the scene
and to establish the precise location and relationship of objects
and evidence. The incident severity will dictate the amount of detail
in your sketch; and whether or not it may have to be redrawn into
a more finished drawing at a later date. Your sketch creates a mental
picture of the scene for those who were not present and will assist
with interviewing witnesses, preparing your report and debriefing
management or safety committees.
While your investigation is a priority so too is returning the area
to production. Sketching the scene allows the investigator to quickly
record, and therefore preserve important information about the scene
as it was found. Ideally, nothing should be moved at an incident
scene before it is photographed and sketched. In fact, drawing the
sketch first helps you focus on what photographs you want to take.
You can also include in the sketch the position from which photographs
were taken which further helps to communicate what took place to
viewers.
The field sketch while not drawn to a precise scale should represent
items in proportion to other items at the scene. Always fill the
size of the paper with the sketch, as it will soon be cluttered
with measurements or objects. If there are a large number of items
to be measured then list the measurements on a separate sheet of
paper. If you want to establish a rough scale, take the longest
measurement at the scene and divide it by the longest measurement
of the paper being used for sketching or the number of squares on
your graph paper. For example, if the longest wall of a room to
be shown in the sketch is 80 feet, and you have 40 squares on the
long side of your graph paper, each square can represent 2 feet.
If the length of your paper is 10 inches, then the scale becomes
one-inch equals 8 feet.
The most useful sketch is a basic floor plan that represents the
scene from an overhead view. If the height of objects is a factor
then a side view sketch may also be required. What's important and
what's not? A general rule of thumb is to include anything that
might remotely be important. Include easily identifiable points
like doors, windows and pillars.
Start with an obvious feature, perhaps the position of the injured
worker, and work either clockwise or counterclockwise, or from one
end to another so that nothing is overlooked. Show the location
of people, equipment, or materials involved in the incident. If
there are liquid spills, skid marks, dust or footprints these must
be noted as they can change or disappear quickly. Thanks to gravity
over 90% of all the evidence you find at an incident scene is on
the ground. Don't walk or drive over it as you enter the scene!
Mark the position of North on the drawing. It doesn't always have
to be at the top. Sketches are more easily understood by others
if the point of entry to the area or room is at the bottom of the
page. In a free corner of the sketch be sure to include information
as to the date, time, place, the nature of the incident, and the
names of the persons measuring and sketching the scene. Include
the notation "Not to Scale" because it's simply not possible to
have a field sketch that is 100% to scale.
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