basic crime scene sketching chapter 2 thanks to special agent thompson for helping mrs. warren put...
TRANSCRIPT
Basic Crime Scene Sketching
Chapter 2
•Thanks to Special Agent Thompson for helping Mrs. Warren put this together
Sketches
• Hand-made pictorial representation of conditions at a crime scene
• Helps to clarify investigative data
• Explains the relative position, appearance, and condition of physical things which may be material to the investigation
Purpose of sketch is for reconstruction of crime scene
When do we sketch?
• Death scenes
• Serious personal injury
• Sex crimes
• Serious property damage
• Whenever necessary to convey the facts
• FBI always sketches
Sketches Supplement Photos
Photographs• Provide great detail• Do not always show
true and accurate relationships
• Cannot determine distances
Sketches• Eliminate
unnecessary detail• Show true and
accurate relationships• Determine distances
Secure the Scene• Exclude everyone without an official function
• Approach scene carefully and systematically Have a plan!
• Preserve the relationships of objects– Do not alter the position of any object until
photographed and recorded– Position, location, or relationship to other items is
often as important as the object itself– Record through notes, photographs, and
sketches
Materials Required
• Clipboard
• Pencil and ERASER
• Ruler
• Tape measures
• Compass
Reference Points
• Must be accurately described on sketch• Must be relatively permanent (likely to still be
there 10 years later• Fixed points
– Door frames– Room corners
• Outside– Utility poles– Manhole covers– Building corners
• Can be created (iron stake)
Three sketch methods1. Baseline
– Used 90% of the time– Establish a baseline (points A and B) and
describe all evidence in relation to these points• Typically use the back of the room, but can use
other places (like the middle of the room)
– Show outline of the room, doorways, and all evidence• Leave out things that are not relevant
– All measurements go on table, no measurements on sketch
Baseline example
Item Baseline Distance from baseline
1 = Casing #1 3 ft. 12 ft. 4”
2 = Gun 5 ft. 8” 7’ 2”
3 = Casing #2 6’ 4” 7’ 2”
4 = Body 17’ 4” 10’ 6”
A B
A = NW cornerB = NE cornerA → B = 24 ft.
N
S
EW
Three sketch methods
2. Triangulation• Quickest method when only have a few
items• Need two reference points• Measure distance to item from each
reference point• Again, put data in a table, not on sketch
itself
Triangulation Example
A B
N
S
EW
A = Base of door frame, west
B = Base of door frame,east
Item A B
#1 12’ 2” 10’ 6”
Three sketch methods
3. Rose Compass• Used by FBI ERT
members• Best for outdoors• Orient with a magnet
compass so that 0° is aligned with north
• Only reference point is the center
• Triangulate to center• Can use iron stake
Item Degrees Distance
1 45 ° 32’ 6”
2 330 ° 28’ 7”
3 85 ° 42’ 1”
Important Considerations
• Write down all measurements• Fill in all details on rough sketch while at
the scene• Do not sketch on the same paper as the
notes• Measurements must be accurate (within
reason)• Critical distances should be checked by
two officers
Required Information
• On ALL sketches include in a title block:– “NOT TO SCALE”– Magnetic north– Case number– Date– Location (address)– Name of sketcher and any assistants
Clean Sketch
• Clean sketch is done with a ruler back in the office– Typically still not drawn to scale– Usually don’t use graph paper
• Retain rough sketch as notes