Crime Scene Sketches
Vocabulary
rough sketchexploded viewelevation
triangulationrectangularcoordinatesbaseline
evidence key
1.Objectives of Crime Scene Sketches
- Eliminate unnecessary objects that have no evidentiary value. (These are in photos, but can be eliminated in sketches.)
- Complement the investigator’s notes and photographs
- Show the accurate location and relationships of the evidence items
- Refresh the memory of investigators
- Illustrate the testimony of witnesses
- Provide factual data for crime scene reconstruction.
2.Rules for sketching
A.Plan a systemic approach that meets the needs of the end goal.
B.Make a rough sketch of the overall layout of the scene.
C.Prepare a detailed sketch of each pertinent area with accurate measurements.
D.Prepare blowup sketches as necessary
1.Bloodstain patterns
2.bullet trajectories
3.areas containing a large number of evidence items
E.Make additional sketches as needed during investigation
1.Too much detail in a small area can be complicated
2.Better to have more sketches than too much info on one page.
F.Always include north arrow on sketch
G.Use accurate measurements (don’t mix measurements – ex. Feet and paces, standard and metric)
H. Make sure measuring tape does not sag.
3.Types of Sketches
A.Quality
1.Rough sketch
a.Drawn by the investigator at the scene
b.Is accurate, but crude
2.Smooth sketch –
a.Uses ruled lines and accurate measurements
b.Is drawn from information from the rough sketch.
c.Is to scale, but should stills say, “not to scale”
d.May be done with ink & template.
3.Finished sketch
a.For inclusion in report, not for court
b.May be enlarged, but not court display size – should fit in case file, flat or folded.
c.May be colored
d.May be completed by hand or computer
e. Includes title, legend, key
f.Still says “not to scale.”
4.Courtroom Display Sketches
a.In color
b.Usually drawn by architect or professional graphic artist or is computer generated.
c.Poster size or show with PowerPoint
B.View
1.Plan view, AKA bird’s eye view. From the top of the area looking straight down on the scene.
2.Exploded view – shows walls and sometimes ceiling
3.Elevation sketches – shows the elevation perspective, as though viewer is standing in front of the scene looking straight on.
4.What to include in the sketch
A.Title
1.Print title directly on sketch
2.Include in title:
a.Name of victim/business
b.Address of crime scene
c.Type of crime or incident
d.Location of crime scene – bedroom, den, etc.
e.Date sketch is prepared
f.Name of person who prepared sketch
g.Name of person(s) who took measurements
h.State if sketch is to scale
B.Legend- show lettering and numbering system for evidence, photo spots and fixed points.
C.Evidence Key – match evidence # with measurements
5.Measurement Techniques
A. Rectangular Coordinates Method
1.Uses two walls
2.Measure each piece of evidence from wall.
ItemNorthWest
17’3”3’4”
22’1”10’11”
B.Triangulation
1.Uses two fixed points
2.Measure distance from evidence to each fixed point
ItemAB
18’2”13’1”
210’2”6’8”