Chemical Methods for Developing Latent Prints

Flashcards covering the chemical reagents, applications, safety measures, reactions, and latent print results used in forensic fingerprint processing.

Ningdrin

A chemical applied by dipping or spraying (waiting $24\,\text{hours}$) to paper, which reacts with amino acids from proteins to form a purplish-blue latent print.

Cyanoacrylate vapor (super glue)

A chemical heated in a vapor tent and used on household items (plastic, metal, glass, skin) that reacts with amino acids, proteins, and fatty acids to produce a white print.

Silver Nitrate

A chemical dipped or sprayed on wood and Styrofoam that combines with chloride from perspiration salt to form silver chloride, yielding a black or reddish brown print under UV light.

Iodine Fuming

A method where iodine crystals are heated in a vapor tent on paper, cardboard, or unpainted surfaces, reacting with carbohydrates to produce a brownish print.

Silver chloride

The substance formed during latent print development when chloride from salt in perspiration combines with silver nitrate, visible under UV light as a black or reddish brown print.

Starch solution

A solution sprayed onto a brownish print developed by iodine fuming to preserve it, since the print fades quickly if not photographed.

Vapor tent

An enclosed chamber used to heat cyanoacrylate or iodine crystals into vapor for developing latent prints on evidence.

Carbohydrates in latent print

The chemical components in latent print residue that combine with iodine during iodine fuming to produce a brownish print.