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Crime Scene and DNA Basics for Forensic Analysts

Documentation - Chain of Custody

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Documentation of the scene begins with the first responder. Police officers are taught the importance of taking notes from the time of arrival. The crime scene investigator documents the scene in the form of still and video photography. Sketches are completed at the scene to illustrate relationships between articles of evidence not easily depicted by photography. The following methods of crime scene documentation are used to provide an accurate representation of the scene.

Methods of Crime Scene Documentation

Type of Documentation


Note Taking

It is important that the responding officers note the condition of the scene as it existed upon their arrival. Note taking should be continuously updated during the course of the investigation.

Investigator's notes might include such factors as:

  • Victim and witness statements
  • Who was present at the scene
  • Lighting conditions
  • Open doors and windows
  • Odors
  • Signs of activity such as food preparation
  • Date and time indicators such as newspapers or mail
  • General descriptions of the scene and surrounding area

Photography and Videography

The primary means of crime scene documentation is still photography. Police officers should have an understanding of the importance of keeping the scene preserved, and not moving anything until it is photographed. The photographer must be able to testify that the photograph is a true and accurate representation of the scene at the time the photograph was taken. Crime scene photographs should reveal a detailed, chronological story of the scene.


Photographs may not always depict spatial relationships between objects; sketches are used to supplement photographs. Sketches can more easily depict the overall layout of the scene and the relationships between objects. Investigators usually complete hand-drawn, rough sketches while at the crime scene. These sketches contain all the necessary information for the investigator to subsequently complete a finalized version.


Image of sketch
National Institute of Justice (NIJ) (see reuse policy).
Image of sketch
National Institute of Justice (NIJ) (see reuse policy).
Image of sketch
National Institute of Justice (NIJ) (see reuse policy).

For courtroom presentation, hand drawn sketches may be converted using computerized programs such as computer aided design (CAD), which provide a dynamic, professional appearance.

Types of sketches may include:

  • Entire Scene - the complete scene with measurements
  • Bird's-eye View – an overhead view of the scene
  • Elevation Sketch
  • Cross Projection Sketch
  • Three Dimensional Sketch

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