Polilight Flare Plus 2 manual –
15
LIGHT APPLICATIONS
SEARCHING FOR LATENT FINGERPRINTS
Option 1: Absorption or Reflection Mode
Fingerprints contaminated with dust, dye, grease and blood or freshly deposited latent fingerprints on
highly polished surfaces like glass or metal, can be searched for using this mode.
A low angle white light is used and no treatment of the print is required.
Option 2: Inherent Fluorescent Mode
Latent fingerprints contaminated with fluorescent matter will show fluorescent properties and glow
under appropriate illumination (photoluminescence).
wARNING
Goggles are necessary for viewing this sort of latent fingerprint:
Use the 450 nm blue band and wear orange goggles for initial searching; then
Use the UV band and wear clear goggles.
Also 505 and 530 light with orange and red goggles should be tried.
When wearing the orange goggles, search for latent fingerprints which will glow. Any contaminated
fluorescent latent fingerprints should be readily detected using this mode. When working in daylight,
screening of the search area is essential. Once a latent fingerprint is located, it is recommended that it
be checked using the other Flare+2 bands to obtain optimum photoluminescence.
For photography, use 565 nm or 590 nm barrier filters (select the most appropriate) and if photography
is to be carried out in daylight, that area must be screened.
Option 3: Treatment with Powders
This step is an alternative to the superglue fuming described in Option 4: Superglue Fuming. It is up
to the fingerprint officers, drawing on their experience, to decide which method should be used. Both
steps are applicable to non- or semi-porous surfaces.
This manual provides general methods on how to approach a problem and so particular powders or
brand name powders have not been recommended. Experienced fingerprint officers will have their
own favourite powders and these should be used.
The following notes are useful as a guide:
Do not over-powder. Subsequent superglue development of latent fingerprints is only possible if there
is minimal powder on the ridges.
Fluorescent powder is of much higher sensitivity than normal powder. Only a very small amount of
fluorescent powder is needed on top of the ridge to produce excellent latent fingerprints, while the
same amount of conventional powder would be almost invisible.
On fluorescent surfaces, good results can be obtained with black, non-fluorescent powders or metal
powders.
On non-fluorescent or dark surfaces, white or silver powder can be effective if used in conjunction with
the strong white light from the Polilight. The angle of incidence of the white light should be varied to
obtain the best results.
On coloured surfaces, try to “remove” the colour by selecting a similar coloured band from the Polilight
Flare+2, then use black or silver powder to achieve the best contrast or use a fluorescent powder.
