Forensic Dentistry, Second Edition

96 Forensic dentistry

Inc., Cuyahoga Falls, Ohio). Mikrosil is a casting putty that was originally

developed for toolmark examinations before being used in the fingerprint

discipline to recover latent impressions from irregular surfaces. AccuTrans

is a relatively new polyvinylsiloxaine casting agent specifically designed for

t he re c ove r y of l at e nt fi n ge r pr i nt s a nd ot he r fore n sic e v id e nc e. B ot h pro du c t s

have also been used as a way of recording friction ridge impressions from

the living and the dead. The casting technique works exceptionally well on

desiccated remains containing wrinkles in the friction skin. This technique

can be used after the fingers have been rehydrated or at a disaster scene

when rehydration is not an option and fingerprints need to be recovered

from remains without delay. The first step is to lightly coat the fingers with

black powder, followed by the application of Mikrosil or AccuTrans, which is

white in color, to the fingers. Mikrosil must first be mixed and then applied

to the fingers with a spatula, whereas AccuTrans comes with an automix

gun option that allows direct application to the fingers. The casting material

must be allowed to dry on the fingers before being peeled off to capture the

print (Figure 6.9). Recovered prints will be in correct position and color

when compared to an antemortem standard.

When all described recording techniques have failed to produce quality

postmortem impressions, images of the friction ridge detail present on the

fingers can be captured with digital photography. The proper selection of

direct, oblique, reflected, or transmitted lighting schemes will enhance the

appearance of ridge detail, often resulting in quality images that can be used

for identification purposes. It is also important to capture 1:1 images of the

friction skin because the photographs will be compared with antemortem

impressions of natural size. If this cannot be accomplished, a scale or object of

a known size should be included in the photograph so that image dimensions

can be corrected through the use of digital imaging software.

AB

Figure 6.8 the recording of a powder impression using an adhesive lifter (a)
and its placement onto a transparent fingerprint card (B).