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 degrees 390’ 185 degrees 120’

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.