Advances in Fingerprint Technology.pdf

een treated with ninhydrin. In addition, latent prints can be first transferred
from the specimen surface to a nitrocellulose membrane and then developed.
In another modification, Knowles 161 reported a radioactive visualization
method. The developed latent print silver image is first converted to silver
bromide, which is then reacted with radioactively labeled thiourea to produce
silver sulfide, and the latent print image can then be recorded by autoradiography.
Nolan et al. 162 reported a method employing scanning electron
microscopy to remove interference from the background.
Recently, Ramotowski 163 compared a series of commercial and laboratoryprepared
PD reagents for effectiveness in developing latents on different papers.
The commercial reagents generally performed adequately, though there can be
problems with the reagents on occasion. Dilute acetic acid (household vinegar)
worked about as well as a pre-treatment as the usual maleic acid. Physical
developers are fully reviewed and discussed by Antonio Cantu in Chapter 7.
Metal Deposition
In 1968, Theys et al. 25 reported that it was possible to detect the presence of
fat films on some surfaces by the selective condensation of metals under
vacuum. This is often called vacuum metal deposition (VMD). Since that
time, several metals have been investigated as possible reagents for the delineation
of latent fingerprints. It was reported that a combination of gold
followed by cadmium treatment produced excellent results. 24 Since cadmium is
toxic, zinc and the combination of gold/zinc have been suggested. 164 Kent et al. 26
reported a fairly high success rate with this technique on polyethylene bags.
Batey et al. 165 indicated the procedure worked well on nonporous paper
and plastic and could be helpful with older items, such as from older cases.
Kent and Stoilovic166 reported successful development of latents with several
metals using DC sputtering, a variant of VMD. Murphy167 reported good
results raising an identifiable latent on a milk carton surface where cyanoacrylate
fuming alone had not sufficed.
Migron et al. evaluated a number of metal deposition and vacuum metal
deposition techniques for detecting both eccrine and sebaceous latent prints
deposited on cartridge cases prior to firing the cartridges in the appropriate
firearm. 168 Some identifiable prints could be developed on brass cases, but
generally, these were difficult surfaces.
Special Surfaces or Situations
Enhancement of Bloody Fingerprints
Special techniques are often required for successfully developing bloody
latent fingerprints. 6,169-171 Bloody fingerprints can often be found deposited