Advances in Fingerprint Technology.pdf

Fluorescein solution (in methanol/water) 1%
Barium sulfate 5%
Flour 5%
Titanium dioxide 0.5%
Cornstarch 89.5%
Fluorescein solution (in methanol/water) 1%
Gum arabic 2%
Cornstarch 98%
Rhodamine B (aqueous solution) 2%
Cornstarch 100%
Fluorescein solution (in methanol water) 1%
Luminescent (Fluorescent and Phosphorescent)
Fingerprint Powders
Many types of powders contain natural and/or synthetic compounds that
fluoresce or phosphoresce upon exposure to ultraviolet (UV) light, laser light,
and other light sources. These types of fingerprint powders are useful for the
visualization of latent prints deposited on multicolored surfaces that would
present a contrast problem if developed with regular fingerprint powder.
Luminescent fingerprint powders have rarely been used in the field. With the
advent of laser detection, however, it was found that dusting the latent prints
with fluorescent or phosphorescent powders greatly enhanced laser examination.
Acridine yellow, acridine orange, coumarin 6, crystal violet, p,p′dichlorodiphenylmethyl
carbinol, 3,3′-diethyloxadicarbocyanine iodide,
3,3′-diethylthiotricarbocyanine iodide, merocyanine 540, Nile Blue perchlorate,
Rhodamine B, Rhodamine 6G, phenothiazine, and many other luminescent
dyes and pigments have been reported to be useful as luminescent
dusting powders for laser examination. Selection of the most satisfactory
powder is largely dependent on the background colors and their luminescent
properties. Good results have been reported with several formulations. 16-20
Metallic (Magnetic, Fine Lead, and Metal Evaporation)
Fingerprint Powders
Magnetic powders are fine ferromagnetic powders that are applied by use of
a magnetic applicator. This method was first reported by MacDonell. 21 It was
found that magnetic powders are particularly successful in the recovery of
latent prints from surfaces such as leather, plastics, walls, and human skin.
The magnetic powder process has also been widely used for processing latent
prints on vertical surfaces. The basic materials used in magnetic powder are
iron oxide and iron powder dust along with other coloration compounds.
Magnetic flake powders developed by James and collaborators 22 have been
shown to be equal or superior to classical “magna” powders in developing