Maintenance of Fingerprint Records

Because fingerprint records are essential in the identification of personnel, they should be kept safe from compromise or accidental destruction.

In the notes of the investigation the investigator records all data concerning fingerprints. This assists him or her in the conduct of the investigation and in later preparation for testimony in court, should that become necessary.

The location at which fingerprints were found at a crime scene are cross-referenced to the crime scene sketch as well as to the investigator's notes.

A chain of custody on all latent fingerprint evidence is maintained at the appropriate office.

When taking inked impressions, the investigator taking the impressions must sign the card or paper for identification purposes. This signature is important in legal proceedings. It is neither necessary nor desirable to advise persons of their legal rights solely for the purpose of taking their fingerprints. Fingerprints are never given, they are taken for the purpose of identification.

CASTS AND MOLDS

LEARNING OBJECTIVES: Define the terms used when referring to casts and molds, and list the materials used in making casts and molds. Explain how impressions found at a crime scene are protected and preserved. Describe the basic methods of preserving impressions through the use of casts and molds. Explain how casts and molds are made in special situations with materials other than plaster of Paris. Describe how casts and molds are marked for identification, and how they are packaged for shipment to a crime lab.

Casts made of impressions found at a crime scene may provide a positive link that a certain person or item was at that particular location.

Casting and molding is the process used to make reproductions of delicate impressions found at a crime scene, such as footprints, tire prints or tool mark impressions, which may have evidentiary value. The process is also used to make reproductions of impressions found on bulky objects that cannot be sent to the crime lab.

The following terms are used when referring to casts and molds:

Cast- a positive impression made from a mold.

Mold- a negative impression. Details appear reversed when viewing the object and the mold together.

Impression-- any indentation from which a cast is made.

Object- anything making an impression.

The following materials are used in the basic method of making casts and molds: 

l Plaster gypsum, sculptor's casting grade, or dental compound. 

. Rubber bowls. Enamelware is suitable but more difficult to clean. 

. Spatula, tapered steel blade, 14-inch. 

. Lacquer, colorless or colored. 

. Lubricating oil, general-purpose. 

. Shellac. 

. Syringe, glass bulb, 4-ounce. A baster of either glass or plastic is available in most exchanges and is a suitable substitute. 

. Talcum powder. 

. Commercial casting and molding compounds.

. Tape, textile cotton, 2-inch, single plain weave, white.

. Ruler. A paper evidence ruler upon which identifying data may be written is recommended.

Reinforcing materials may be made of any readily available material, such as fine-mesh chicken wire, wire screen, grass, gauze, coat hangers cut to desired length, twigs, or other small pieces of wood.

An earthen dam maybe built to form a frame around _{footprints, or tire prints.} Linoleum, lead strips, metal venetian blind slats, or wood specially cut to form a rectangular frame may also be used.

RECORDING IMPRESSIONS

When an impression is found at a crime scene, the first necessary action is to protect it from destruction regardless of where it is found. This may include covering it with an object such as a trash can lid or cardboard box if it is small, or roping it off and posting guards if it is a large area.

Photographing

The next action is to photograph the impression. First, an area photograph should be taken to show the impression's location in relation to other objects.

Next, a closeup photograph of the impression should be made. The camera should be placed so that the plane of the film is parallel to the ground. A flash should be used at all times. It should be held close to the impression at an angle since the oblique light will reveal more details. A closeup photograph should be taken with a ruler alongside the impression so the proper scale can be determined.

Identifying data should be written on a paper rule or other piece of paper and placed in the photograph also. It should include the date, case number (if known), your name, exhibit number (if known), type of film used and camera setting (F stop).

Sketching

The location of the impression should be included in the crime scene sketch, with appropriate measurements. Any distinctive characteristics such as trademarks, nail holes, cuts, scars, or other imperfections should also be drawn in the sketch. Include measurements and other descriptive data in your notes. After this procedure is followed make a cast of the impression.