Advances in Fingerprint Technology.pdf

Collin and Thomas (U.K., 1972). According to Goode and Morris, 13 Collin
and Thomas investigated the use of one of the classical silver physical
developers to enhance prints developed by the vacuum metal deposition
process. The idea was sound. These authors knew that silver physical developers
detect very low levels of silver metal and other metals. It is, for example,
one of the most sensitive methods that Feigl 11 cites for detecting silver (his
book was first published in English in 1937). Thus, they reasoned that because
the vacuum metal deposition process, after the initial deposition of gold,
deposits zinc or cadmium all over the surface and in the fingerprint furrows,
but not on the fingerprint ridges, then an Ag-PD should enhance the furrow
regions. They noted the potential of its use but were limited by the instability
of the classical Ag-PD they used.
Fuller and Thomas 14 (U.K., 1974). These authors also investigated a classical
Ag-PD for visualizing latent prints on fabrics and paper. They used the
Metol/citric acid reducing agent in their Ag-PD. The interesting part of their
work lies in their Appendix 1 (process modifications). It is surprising that
many of the ideas they had are now being further investigated. For example,
regarding their suggestion to use metals other than silver, Dr. Kevin Kyle of
the Special Technologies Laboratory (a Department of Energy [DOE] Laboratory
located in Santa Barbara, CA) has investigated a copper-based physical
developer. The DOE funded this project during 1998–1999 and the U.S.
Secret Service managed the research. Other ideas of Fuller and Thomas
include sequential treatment with Ag-PD components and film-transfer
methods.
Morris 15 (U.K., 1975). Morris was the first to document the use of the
“Philips Physical Developer” (a name given by Morris to the “FC-1” silver
physical developer formulated by Jonker, Molenaar, and Dipple in The Netherlands)
for visualizing latent prints on paper. It uses the reversible ferrous/ferric
redox couple with citric acid for the reducing agent. The FC in
the Philips formulation FC-1 stands for ferrous/ferric citric. In our opinion,
this is Morris’ Ag-PD pioneering work. It introduced the currently used Ag-
PD. Morris clearly saw the potential of the Ag-PD for visualizing latent prints
on water-soaked paper (he obtained prints even after 12 days of immersion).
He saw it as a post-ninhydrin reagent. He also provided a hypothesis for how
the developer works, proposing that “trigger” materials exist on the latent
print residue that act as catalytic nuclei and initiate the physical development
process (similar to the silver and silver sulfide specks on the photo-exposed
silver halide crystals in photography). These “trigger” materials include: (1)
wax esters (lipids) because these can strip away the surfactant shell from
(spontaneously formed) silver nuclei formed in solution, and (2) chloride