Advances in Fingerprint Technology.pdf

illumination is often done in conjunction with metal salt post-treatment of
ninhydrin-developed latents. Accordingly, much of the information was presented
starting on page 127. Here, the underlying principles and some more
recent developments are discussed further.
As early as 1937, scientists suggested that alternative light sources (other
than room light) could be used for the enhancement and visualization of
latent fingerprints. High-intensity lamps, UV light sources, lasers, and xenon
arc lamps have been utilized in the development of latent prints 16-19,77,230,231
and have produced better latent print images than regular room light.
Dalrymple, Duff, and Menzel 230 first reported the technique of laser
detection of latent fingerprints by their inherent luminescence. Subsequently,
a number of alternative procedures were suggested. Various fluorescent powders
such as Mars red, hi-intensity fingerprint powder, Red Lake C, and
naphthol red B (2′-naphtholazo-1-bromo-2-naphthol-1′-sulfonate) have
subsequently been employed to enhance the detection sensitivity of the laser
procedure. Other fluorigenic dyes, such as coumarin 6, Rhodamine 6G,
Rhodamine B, Aquabest orange fluorescent pigment, phenothiazine, Nile
Blue A perchloride, and 3,3′-diethylthiatricarbocyamine iodine, have also
been used to enhance laser light detection of latent prints. 16-20 Initially, it was
recognized that inducement of the intrinsic fluorescence of latent fingerprint
residue required wavelengths shorter than were available in any commercial
lasers. Thus, use of compounds with desirable excitation and emission wavelengths
that would also adhere to fingerprint residue or interact with ninhydrin-
or cyanoacrylate-processed latent prints greatly extended the
applicability of laser processing. 16,17,20,75,148,232 These chemicals react or interact
preferentially with components in fingerprint residues to form luminescent
reaction products. Of all the different strategies tried, post-treatment of
ninhydrin-developed latent prints with zinc chloride has proved the most
robust for laser processing. 77,124 Other types of lasers such as dye lasers and
copper vapor lasers have also been used for latent print detection. A review
of the use of lasers for the detection of latent prints can be found in the first
edition of this book. 131
Bramble et al. showed that shortwave UV illumination produced as the
fourth harmonic of a Nd:YAG laser (266 nm) gave good results with a series
of sebaceous prints on white surfaces, yielding more prints of good quality
than several visible luminescence methods. 233 Ben-Yosef et al. reported similar
results, although noting that the technique was primarily applicable to
searching textiles and other substrata for biological fluids. 234 Shortwave UV
illumination did not give good luminescence results with eccrine prints.
These methods take advantage of the intrinsic fluorescence properties of
latent fingerprint residue and may be preferable to more widespread methods