Introduction
Fingermarks remain one of the best forms of evidence for the
identification of an individual and, as technology advances the
search for new reagents with increased sensitivity and
specificity continues.
The type of physical or chemical enhancement process used
to visualise latent fingermarks depends on the type of surface
the fingermark is deposited on.
Two traditional methods for latent fingermark detection on
porous surfaces, such as paper, are 1,8-diazofluoren-9-one
(DFO) (Fig. 1) and ninhydrin (Fig. 2), with or without
secondary metal salt treatment.
The application of ninhydrin to the development of latent
fingermarks was first proposed in 1954 by Oden and von
Hofsten [1]. Ninhydrin reacts with the amino acids present in
the latent fingermark. This reaction causes the ridges to appear
dark purple in colour due to the formation of Ruhemann’s
purple (Fig. 3).
Ninhydrin treated fingermarks can be further enhanced with
metal salt (usually cadmium or zinc) treatment to give strongly
luminescent fingermarks when cooled with liquid nitrogen.
1,8-Diazafluoren-9-one (DFO), introduced by Pounds et al.
in 1989 [2], also reacts with the amino acids in the latent
fingermark to give pale purple ridges upon the application of heat. Strong room temperature luminescence results without
any further treatment.
DFO is regarded as the more sensitive of the two reagents,
however ninhydrin is the most widely used due to cost and
strong initial colour.
IntroductionFingermarks remain one of the best forms of evidence for theidentification of an individual and, as technology advances thesearch for new reagents with increased sensitivity andspecificity continues.The type of physical or chemical enhancement process usedto visualise latent fingermarks depends on the type of surfacethe fingermark is deposited on.Two traditional methods for latent fingermark detection onporous surfaces, such as paper, are 1,8-diazofluoren-9-one(DFO) (Fig. 1) and ninhydrin (Fig. 2), with or withoutsecondary metal salt treatment.The application of ninhydrin to the development of latentfingermarks was first proposed in 1954 by Oden and vonHofsten [1]. Ninhydrin reacts with the amino acids present inthe latent fingermark. This reaction causes the ridges to appeardark purple in colour due to the formation of Ruhemann’spurple (Fig. 3).Ninhydrin treated fingermarks can be further enhanced withmetal salt (usually cadmium or zinc) treatment to give stronglyluminescent fingermarks when cooled with liquid nitrogen.1,8-Diazafluoren-9-one (DFO), introduced by Pounds et al.in 1989 [2], also reacts with the amino acids in the latentfingermark to give pale purple ridges upon the application of heat. Strong room temperature luminescence results withoutany further treatment.DFO is regarded as the more sensitive of the two reagents,however ninhydrin is the most widely used due to cost andstrong initial colour.
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