|Posted on Thursday, February 02, 2006 - 09:32 pm: ||
One sequence (of many) could include the following steps:
1 - Visual exam with direct white light; Eighteen steps might seem extensive, but on many surfaces you will do even more than shown above because of the need to photographically record impressions each time they appear a little bit better (greater contrast or more complete ridge detail than visible with prior steps). If impressions of value are not photographed, they may deteriorate or disappear while you are attempting to visualize or enhance additional prints.
2 - Visual exam with oblique white light;
3 - Visual exam with direct reflection white light;
4 - Exam for any inherently luminescent impressions via laser or alternate light source;
5 - Reflected Ultraviolet Imaging System (RUVIS) exam;
6 - Iodine fuming, with the hope that some of the oily, translucent tar residue may be enhanced (temporarily);
7 - Cyanoacrylate fuming (making sure that your test strip develops well, of course);
8 - Visual exam with direct white light;
9 - Visual exam with oblique white light;
10 - Visual exam with direct reflection white light;
11 - Reflected Ultraviolet Imaging System (RUVIS) exam;
12 - Dye staining with a luminescent dye (such as
13 - Exam for any dye-stained luminescing impressions via laser or alternate light source;
14 - Dust with your choice of contrasting color fingerprint powder;
15 - Visual exam with direct white light;
16 - Visual exam with oblique white light;
17 - Visual exam with direct reflection white light;
18 - The final step for non-porous surfaces, after you have done everything and have nothing to lose, is as follows:
Pour some of the contrasting color dusting powder onto a sheet of paper; put on a pair of surgical gloves (or even cloth gloves) and pat the front of your glove-covered fingers into the powder; rub the powder from the gloves gently over the surfaces you have processed for latent prints... the result being that in some instances, you will enhance ridge detail that was previously not identifiable via any of the prior steps. The powder tends to "build-up" on both sides of the three dimensional ridge detail developed in cyanoacrylate ...often producing reverse color impressions with the powder filling-in the furrows. Developed in the early 1980s by Mike Grimm and colleagues in Virginia, this rubbing technique has been successful on many non-porous surfaces at many laboratories in the US and overseas.
|Posted on Wednesday, February 01, 2006 - 10:43 am: ||
There are multiple items including a non-porous wood handle and plastic that appears to have come from a sky light.
|Posted on Thursday, January 26, 2006 - 07:21 pm: ||
Shauna, please describe the items/surfaces bearing the prints deposited in tar.
|Posted on Wednesday, January 25, 2006 - 02:16 pm: ||
I am currently working a burglary case where the suspects had roofing tar on their hands and subsequently left prints on other objects. Does anyone know of any enhancement processes or had to work with this type of situation before?