Another option is preservation of dust prints.
Then there are several options:
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Always photograph first!
Remember, the last two lifting techniques result in a “reversed” image. Always explain what you did to document the dust print so that the examiner knows how to proceed.
Gel lifters are made of a thick, non-aggressive, low-adhesive gelatin and permits the lifting of traces from almost every surface, including porous materials, such as paper or cardboard.
Lifted prints can be collected for photography or closer examination.
There are three layers: the carrier, the adhesive, and the cover sheet.
Most commonly you’ll find three colors of lifters: black, white, and transparent. The black and the white lifters have a carrier of linen rubber. The transparent lifters have a clear polyester film as a carrier.
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Due to this, gelatin lifters are not a permanent storage solution for prints or trace.
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Remember, these are picking up trace, so you should not reuse a lifter either on the same case or between cases.
However, once a print fades away, consider reusing them for training purposes if they have no biological contamination, and if they are still sticky. But never on real evidence.
The Electrostatic Dust Lifter (ESDL) consists of a high voltage power supply, a steel ground plate, and a metalized lifting film.
As high voltage is applied to the lifting film, it takes on a negative charge and the plate becomes positive. Any dust present under the film will take on a positive charge and be attracted to the negative film.
It can be used on rough floor, irregular surfaces, and even carpet, but is not recommended for conductive surfaces such as cars, tinted windows, or exterior metal doors but it can still be used if you follow manufacturer’s safety procedures, and there’s an article in your readings on how to do it.
Caution - this machine will shock the living daylights out of you. No really, it will.
This is a fragile substrate, so transport to the lab taped to a flat box (un-used pizza boxes work perfectly) and photograph ASAP.
Just like the gel lift, this will be a reversed photo. Note that in your report and in any follow up to the print examine.
When collecting comparison prints, remember to photograph first before adding anything.
Some methods you can use to collect your comparisons include using an ink roll and then transfer to white paper (excellent for tire impressions), BioFoam or similar items sold by forensic companies, or simply take the whole shoe, tool, or tire! This is harder, but not impossible, when it’s teeth marks!