Developing latent prints on the adhesive side of tapes
There’s an expression among the “fit-it” community that goes like this, “If it doesn’t move and it should—use WD-40. If it moves but shouldn’t—use duct tape.” The criminal element seems to have adopted the latter advice.
Duct tape has become the bonding method of choice—investigators find it used on hostages, rape and kidnap victims and other innocent bystanders.
While many brands of duct tape feature a smooth outer surface that often harbors latent prints, the adhesive-side of this same tape may provide a bounty of latent print opportunities. Using a simple mixture of finely milled iron oxide powder and a surfactant that is brushed onto the adhesive (sticky) side of the tape, the latent print expert can quickly develop some of the most outstanding, sharp, well-defined latents he has ever seem. And no one at the moment has determined exactly what the black, soapy goop is reacting to.
Some theorize that this developing solution is reacting to oily deposits while other experts think it may be an accumulation of dead skin cells. Regardless of why this works, the point is that it does work and latent prints from anyone who had occasion to touch the adhesive side left his/her calling card.
Here’s how to mix up and use a batch of Adhesive-Side Powder (ASP):
1. Choose the powder for best photographic contrast.
2. ASP must be premixed before use. Use a clean glass or plastic mixing bowl.
3. in a clean mixing bowl, add one teaspoon of the powder giving the best contrast against the background color of the tape. Note: Dark ASP works best on gray duct tape.
4. Add one teaspoon of eZFLO working solution to the bowl.
5. Mix the solution and the powder together using a clean brush such as the Regular Latent Print Brush (118L). Stir until the mixture has a frothy appearance.
6. Brush the mixture onto the sticky side of the tape. Allow 10 seconds for setup, and then rinse under cold, running water. Prints should be immediately visible.
Please note that ASP formulations are also available in pre-mixed solutions.
For more information on latent print development techniques and processes like ASP, download the free Overview of Latent Print Development Techniques. http://www.sirchie.com/Assets/Manuals/pdf/LP%20Dev'mt%20Tech_TB02-102ENG-REV2E.pdf
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