Polilight Flare Plus 2 manual –
13
LIGHT APPLICATIONS
APPLICATIONS AT SCENE OF CRIME
The following examples describe some methods of detecting latent fingerprints on various surfaces
using the Polilight Flare+2. Clearly, these are not the only ways in which the Flare+2 can be used and
experimentation is encouraged, especially when dealing with latent prints on unusual surfaces.
When working in the field, the composition of the absorbing substance in the latent print will be
unknown. This is determined by experimentation; varying the light from various heads systematically
through the whole wavelength range.
At the same time, the barrier filter (goggles) may need to be varied in order to help distinguish
between the fluorescence from the latent print and that derived from the object upon which the latent
print has been deposited.
Shoe Prints
Note
When searching a crime scene, one of the first things to look for is shoe prints. The
floor area must be protected against people at the scene introducing new footprints.
The Polilight Flare+2 can be used for the discovery of shoe prints and similar marks on flat surfaces
such as ceramic or plastic tiles, varnished wooden floors and shiny concrete. However, it cannot be
used on rough, porous or textile surfaces like carpets.
Using a very oblique angle, the powerful white light together with the 60 x 1 degrees filter, is the most
useful for this purpose, although it is recommended that all the Polilight bands be used for scanning,
until the right band shows the best results.
WARNING
Amber goggles should be worn to protect the eyes.
General Fluorescent Method
Very rapid scanning for photoluminescence traces such as transferred fibres, paint, grease, semen and
vaginal fluid, sweat and urine can be achieved using the UV and 450 heads to scan the general area.
Light from the 450 nm blue head is recommended for general searching and the operator should wear the
amber goggles provided. If some fluorescence is found, the other bands should be checked in case better
photoluminescence can be induced in the sample or the luminescence of the background can be modified.
Sometimes it may be necessary to use barrier filters (545, 590 or 600 nm – optional extras) instead of,
or in addition to, the goggles to reduce the red luminescence background, which often passes through
the goggles.
The UV band together with the clear or yellow goggles, are also useful for general searching.
Example: Viewing an old couch under UV light and using clear goggles will often bring up stains and
fibres. Viewing the same couch under the 450 nm band using orange goggles can often bring up a
different set of stains and fibres not seen under the UV light.
This type of searching is best carried out at night or in a darkened room. In exposed situations,
screening of the exhibit from external light will help but is only likely to reveal strongly fluorescent
samples. After the preliminary searching, it is recommended that all mobile exhibits be taken to the
laboratory for more detailed inspection under totally dark conditions.
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