A small particle (iron oxide) suspension for detection of latent fingerprints on smooth surfaces

Abstract

A small particle suspension of iron oxide black (Fe 3O 4) powder has been formulated for developing latent fingerprints on smooth surfaces. This new reagent was compared with the reported reagents known as small particle reagent (SPR) or molybdenum disulfide in suspension, and was found to be superior with regard to sensitivity, clarity and contrast. Excellent results were obtained on dry, wet or frost-covered smooth surfaces irrespective of whether the latent fingerprints were new or old. The developed black fingerprints are cleared very easily by washing with soap and water. The method was tested on specimen fingerprints taken from thirty donors. Scanning electron microscopic studies were performed on several powders to determine the particle size and to correlate it with the behaviour of small particle suspensions prepared from these powders.