Crime Scene Investigation: A Guide for Law Enforcement

Overview

• Published by: Bureau of Justice Assistance, U.S. Department of Justice
• Project Director: Kevin Lothridge
• Project Manager: Frank Fitzpatrick
• Developed by: National Forensic Science Technology Center

Documentation (Section C3)

Principle

• Assessment of a crime scene determines necessary documentation: photography, video, sketches, measurements, notes.

Policy

• Documentation responsibility lies with the investigator(s) in charge.

Procedure for Documentation

1. Review Scene Assessment:
   • Determine the type of documentation needed.
2. Coordinate Documentation:
   • Integrate photographs, video, sketches, measurements, and notes.
3. Photography:
   • Capture scene with overall, medium, and close-up coverage.
   • Include evidence with/without measurement scales.
   • Photograph victims, suspects, witnesses, crowd, vehicles.
   • Consider additional perspectives.
4. Video Recording:
   • Optional and supplementary to photographs.
5. Sketch Preparation and Measurement:
   • Include immediate area, relative location of evidence, room layouts.
6. Note Generation:
   • Document scene location, arrival/departure times, scene description, transient evidence, and any deviations from standard procedures.

Sketching

Equipment Needed

• Graph paper, measuring tape, walking wheel, folding rule, ruler, clipboard, compass, personal protective equipment, flashlight, notebook, pencil.

General Considerations for Sketching

• Sketches are necessary for spatial relationships and proportional measurements.
• A rough sketch is the initial sketch drawn before any alteration of the scene.
• Multiple rough sketches may be needed.
• Sketches should include details such as room dimensions, object sizes, and references points.
• Use fixed points for measurements; do not alter rough sketches post-scene.

Information to Document

• Record incident details including who, what, when, where, why, and how.
• Graph paper sketches should include a title block and legend.
• Ensure measurement accuracy and define scale in sketches.

Categories of Sketches

1. Perspective: Depicts objects with vanishing points, showing depth and distance.
2. Projection: Contains one viewpoint, commonly a bird’s eye view.
3. Schematic: Represents sequence of events, such as bullet trajectory.
4. Detailed: Describes small areas not incorporated into larger sketches.

Creating a Projection Sketch

• Determine viewpoint (overhead or exploded).
• Draw outlines to scale including accurate measurement of perimeters.
• Use consistent measurement units; confirm with another officer.
• Methods for accurate measurements include triangulation, rectangular coordinates, polar coordinates, and transecting baseline.

Measurements Techniques

1. Triangulation Method: Uses two fixed points for measurements.
2. Rectangular Coordinate Method: Measures distances to objects from two perpendicular lines.
3. Polar Coordinate Method: Suitable for outdoor scenes with a single reference point.
4. Transecting Baseline Coordinate Method: Uses a baseline for measuring numerous objects.

Finalizing Sketches

• Sketches should be marked as "Not to Scale" to prevent legal controversies.
• Legend and notes should include all details and updates.
• Note-taking is crucial and should continue throughout sketching activities.
• Final sketches can be completed by the originator or a draftsperson.