FBI Handbook of Crime Scene Forensics by Federal Bureau of Investigation Read Free Book Online Page B

Examinations and Packaging and Shipping Evidence .
Pack ink evidence separately from any document or surface with ink marks.
    Latent Print Examinations
    Case Acceptance Policy
    Because of the increasing casework demands of the FBI’s primary mission, protecting the United States from terrorist attacks, the FBI Laboratory will no longer accept routine cases from state and local agencies in which latent print examination services may be obtained from within the submitting agency’s system. The future acceptance of any state and local cases generally will be based on the submitting agency’s lack of access to the same techniques or services provided by the FBI Laboratory, the unusual technical nature of the case, or the circumstances surrounding the case, e.g., cases of a high-profile nature or cases that also involve FBI field offices.
    Developing Latent Prints at Crime Scenes
    The Laboratory is the best place to develop latent prints; however, it is sometimes necessary to develop latent prints at crime scenes. Caution should be taken to prevent destroying latent prints. The following measures ensure that crime scene latent prints are protected:
Photograph latent prints prior to any processing.
Examine all evidence visually and with a laser or an alternate light source before using any other latent print development process.
Photograph latent prints developed with fingerprint powders before lifting them.
Black, gray, or white powder can be applied to a surface with a variety of style of brushes. The color of the powder should contrast with the color of the surface (e.g., black for light surfaces and gray or white for dark surfaces).
Use a short-hair brush or cotton to remove excess powder. Use caution when powdering. Avoid overbrushing latent prints and losing clarity.
Use transparent tape or black-and-white rubber lifts to lift latent prints.
When transparent tape is used, the color of the backing card should contrast with the color of the powders (e.g., white backing card for black powder).
When using latent print development processes, refer to the manufacturer’s instructions and the Material Safety Data Sheets. Use personal protective equipment (e.g., safety glasses, masks, gloves, smocks).
The Processing Guide for Developing Latent Prints is a comprehensive guide to latent print processes and protocols. Refer to this publication to ensure that proper processes are applied in the recommended order. Following this guide will maximize the potential to develop latent prints and will preserve evidence if other forensic examinations are required. The guide is available at http://www.fbi.gov/hq/lab/fsc/backissu/jan2001/lpu.pdf . Law enforcement personnel may request the Processing Guide for Developing Latent Prints in field-manual format by faxing a request on agency letterhead to 703-632-8374.
    Photographing Latent Prints
Use a tripod and cable release when photographing latent prints.
Use a 35 mm or medium-format camera with a macro lens capable of half-size to full-size reproduction.
Photograph latent prints at each step in the processing sequence before moving to the next process.
Photograph latent prints developed with fingerprint powders before lifting them.
When possible, use ISO 400 film. Set the lens f-stop to the smallest possible aperture while using the camera meter to adjust the camera’s shutter speed to obtain proper exposure.
Take three exposures of each latent print by bracketing:
Original exposure.
One-stop underexposed image.
One-stop overexposed image.
Photograph latent prints individually. This ensures that the target latent print is in focus.
For reference purposes, photograph latent prints close to one another in one frame, if possible.
Fill the frame completely.
Photograph latent prints with an identification label that includes a scale, reference number, date, collector’s initials, and location of the latent prints. The identification label should be placed on the same plane as the latent