Crime Scene Investigation & Documentation

Purpose of a scene search

To obtain physical evidence pertinent to solving a crime

Physical Evidence Physical Evidence must be

recognized, accurately documented, properly collected and transported, and a chain of evidence must be maintained before it can be of forensic value.

Manpower and fiscal restraints must be considered relative to the nature of the crime.

Preservation of the Crime Scene

First officer on the crime scene must: Obtain medical assistance Arrest the perpetrator Secure the scene (to prevent destruction

of evidence) -- May require limiting access to a single room in a motel or sealing off an entire block after an urban fire

Observation is key

Count

Finished files are the results of

years of scientific study combined with the

experience of many years

Once secure, always approached the scene:

in a serious manner (never casually) in an open, unbiased manner (never

have preconceived ideas). Murders have been bungled because the

investigator thought it was a natural death or a suicide

Steps in Scene Investigation

Hands in pocket walk-through to observe scene and plan approach.

Minimum number of investigators. Establish a path of entry and exit

(path least likely used by the criminal).

Never take convenience and expedience over thoroughness.

Homicide Scene

Efforts of Law Enforcement and Medical Investigator must complement at the scene.

Medical Examiner is there just to see body in perspective – their hands on examination happens back in the autopsy lab

Documentation of Scene

Notes Photographs Diagrams

Scene Notes

Accurate Brief Legible Tape record, then transcribe later—

carefully!

Photography

Color photo’s Mirrors in tight places Photograph objects before moving Photograph the scene thoroughly Use scales in photos Videos (beware of the sound) Fisheye Lenses and Virtual Images

Hand Drawn Diagrams

Entirety of the scene can be illustrated

Insert labels and distance measurements

Document the location and relationship of evidence obscured by vegetation, soil, ashes, or other materials

Two Types of Drawings

Rough Sketch Finished Drawing

Rough Sketch

Made by the investigator on the scene Not necessarily drawn to scale

(includes proportions and distances) No changes to sketch after leaving

scene Soft pencil, graph paper, straight

edge, compass, clipboard

Elements of Sketching

Scale diagram appropriately Compass Direction with north arrow lnclude essential items only Document the scale (words or figure) Legend with symbols to identify

objects Title with case identification, location,

date, and the sketcher

Documenting the Location of Evidence

Rectangular Coordinates Polar Coordinates

Rectangular Coordinates

Triangulate from perpendicular boundaries

Bed

Dead guy

2’ from N wall

18” from W wall

Polar Coordinates

Degrees from north and distance

135 degrees390’

185 degrees120’

Global Positioning System (GPS)

for remote areas

Projection Sketch

a three-dimensional sketch to allow better illustration of evidence on walls

Bed

Dead guy

2’ from N wall

18” from W wall

B

A-E – bullet holes

C

D

E

A

Finished Drawing

Primarily for courtroom presentation

Remember:

When a crime scene is investigated, it is destroyed. The only place it will ever exist after the investigation is in the investigator’s notes, photographs, and diagrams.