CLPEX Chat Board

Hope someone can assist!
I have been looking for a study (or paper) that describes the liklihood of DNA transfer as a result of continued use of the same fingerprint brush, or powder for that matter. Our agency currently does swab for touch DNA in some instances, however the swabbing takes place prior to "powder processing". I have tested the "spray or aerosol" powder systems and have been suprisingly pleased with the results they can provide in some instances. However I have yet to commit to disposable brushes, unless the scene is "too" contaminated. Recently I learned that our State Lab has a great concern about the potential for DNA transfer through the use of common brushes. They use "disposable" brushes for their work, and then give them to the agency they're assisting when they're done.....sounds a bit hypocritical to me. Anyway, I was hoping to find some information out to determine if our SOP's need to be changed.

Thanks,

Dave Tivin, West Chester Police
West Chester, Ohio

This is pretty lame (replying to myself)!! I have located some earlier threads on this site that seem to assist me. If anyone has anythng more recent, I would still appreciate it.

Thanks

Our unit currently uses disposable brushes and shaker jars, except when we use magnetic powder and then we just make sure to clean the wand thoroughly before and after use. We're currently experimenting with a UV chamber and washing the brushes after use with ethanol and/or a bleach solution (surprising to me they actually dried fairly well when using just a standard swab dryer). There were um... what I was told interesting results the first time the experiment was run so they're trying it again. If I get an update I'll let you know since I doubt they're looking to publish the results and just want to know for internal purposes if we can reuse brushes without significant risk of contamination.

Thanks,

I've actually run across a lot of info over the past 2 days. I think the safest protocol is to swab prior to dusting. The ability to visualize latents after CA fuming (prior to dusting) also allows for the determination as to whether they would be better served as "swabbing candidates" versus "lifting candidates".

Actually today I just recieved the latest JFI and noted the article that speaks to the use of "Aerosolized Application" of fingerprint powders. Our experience with them (mostly smooth, horizontal surfaces) has been positive. The black & white powders are applied very evenly. I was less impressed by the fluorescent applications.

Except that what appears to be an unsuitable latent print can be "cleaned up" by lifting it several times. Also, I've had several blister pack plastic wrapped items upon which latent prints did not develop with CA and were only enhanced with powder. Not to mention that some people probably believe that if you're CA fuming an item long enough to make a determination about whether or not to lift or swab, you may have CA fumed the item way too long. At that point, why not just dye stain it and then you don't have to worry about contamination from powders or brushes?

There are times when swabbing prior to processing is probably best, but I personally would stick to highly textured areas where you know that latent prints are not likely to develop. If I'm going to swab before I process an item (very very rarely I might add) it's going to be prior to CA fuming and my concern whenever I do that is slippage of the swab or accidentally swabbing over/into an area where a latent print could have been.