CLPEX Chat Board

In the recent JFS journal (AAFS publication), there was an article regarding the processing of rocks and stones for latent prints. I read through the article with interest, hoping to find out about a technique that would require our CSIs to do even more work at burglary scenes where rocks or stones were used to break in to a residence or business. Midway through the article, the author(s) cite the HOSDB Manual for processing rough, non-porous surfaces. In the article, they say that powdering is a step that should be completed before cyanoacrylate fuming. I don't ever remember being trained to powder something before I fume it since the powder may cover or coat the latent print detail and would prevent the CA from adhering properly. I emailed the author and they graciously sent me a copy of the page in the manual that illustrates the flow chart (#2) that does indicate that powdering is recommended before CA.

Has anyone, or does anyone, routinely do this in casework? I had to look at the FBI's latent print processing guide and they have powdering after CA fuming--like how I do it. I'm just a bit confused now and was wondering if there is a reason why I've been trained to fume then powder or if it really matters?

Josher -
I have had some occasional cases where powdering has been performed at the scene, and then cyanoacrylate has been used at a later date in the lab - these cases were where the evidence item had been seized for a different reason after the initial fingerprint examination on scene, and as a matter of course they submitted it for all testing at the lab. In those cases, the cyanoacrylate had not been impeded by the powder - the superglue merely developed the same areas that the powder did.

However, this was not standard protocol for us to do. Our standard protocol for exhibits at the lab was superglue first, then enhancement methods second (where powdering was one option of many). My point though is that my experience has been that doing it the other way around does not seem to affect the subsequent superglue fuming. Obviously a proper validation study would be needed for that - not sure if one already exists??