Semi-porous processing for latent impressions??? help

[sgustavson]

Hello All,

It's Sally again.... I figured I had such amazing feedback about the tracing paper I might as well give my next question a go.

I am wondering what the Forensic community does in regards to processing semi-porous items (such as cardboard jewelry boxes, magazine papers, etc) for latent impressions. We do Non-porous processing (superglue funimg, Dye stains, powder) and then porous processing techniques (DFO, NIN, ZnCl, PD) on these items. However, I feel like the dyestains seem to inhibit the ability to develope prints with the nonporous processes. I have been using Aqueous Rhodamine, but I still dont feel 100% comfortable with this methond. Does anyone have any suggestions for processing sequences? or suggestions?

Thanks,

Sally

[sharon cook]

I always used to have excellent results from CA-fuming, "huffing", and magnetic powder. "Huffing" is when you blow a little moisture-ladened breath on the surface then immediately hit it with the magnetic powder. If you go back over the print with the magna powder, it will disappear, I've found. This is something you have to practice, but I've had great success with PVC pipe, plastic bags, and the shiny paper of jewlery boxes and magazines.

[garywood702]

Sally,

I have had good results CAE fuming cardboard jewelry boxes as long as they have some sort of finish (textured/smooth/glossy). The same with glossy magazine pages and glossy brochures. I would not advise using liquid dye stains on these items though. Magnetic powders would be your best bet after photographing any CAE developed prints. Do you have a RUVIS? If so, that should be your next step after CAE fuming and before magnetic powders. If not, then mag powder after photographing any CAE developed prints.

[Diana Tabor]

I have had good results with Superglue fuming, magnetic powder, DFO, and then ninhydrin on these types of evidence. DFO usually seems to work better than ninhydrin, but often the surface has some images and/or writing on it. The best results I can recall have been on magazine papers used as bindles.

[Pat]

I received a box of Kellogg's Corn Flakes for fingerprinting one time that had been seized with $88,000 cash in it. What's the best method to process a Kellogg's Corn Flakes box? I didn't know. So I went out and bought a box of Kelloggs corn flakes, cut the box into a dozen pieces, deposited latents on each piece, then tested for the best results. It turned out that hot breath (huffing) and mag worked the best, no prior CA fuming. So I used that method on the evidence and identified a drug smuggler/runner.

So my suggestion is to run some validation tests, not just on the methods you use in your lab, but on the various methods for a variety of specific surfaces. A cardboard box, for example, can be cut into a bunch of pieces and each piece processed with a different method or sequence of methods. That way, you aren't just taking the word of somebody on the chat board, you are learning for yourself in a way that allows you to use the method with confidence and then testify to it in court as an expert.

[Mark]

We typically go the route of superglue/magna powder/dyes stains(sometimes aqueous) for the glossy outer surface, but do follow up with dfo/nin/pd depending on the item to try to develop prints deposited on the non-glossy side (i.e., the underside of flaps of the opening to an ammunition box). As far as "huffing" goes we have strayed away from this technique in this day of DNA analysis as this could (I stress could) contaminate the item for potential DNA swabbing.

[garywood702]

Mark,

I'm curious to know how you prevent dye stains from being absorbed by semi-porous surfaces? It has been my experience that the dye stain permeates the finish and is absorbed by the paper which creates considerable background noise when trying to photographically document the developed fingerprint. Which dye stain/s are you using? Perhaps the problem I'm having is with my choice of dye stain.

The post mentioning validation tests is very sound advice indeed! Good job on nabbing the drug dealer! However, Mark does bring up a valid point with the "huffing" technique. One does need to assess whether the item in question might be tested at a later date for DNA while being mindful that such a test request could come from the defense. Since it seems many fingerprint cases are being cross checked with DNA analysis these days I would suggest being careful about potentially contaminating evidence with one's own DNA. Another consideration with DNA is the use of a RUVIS with short wave UV light source. It is my understanding that the short wave UV light will degrade DNA so if one is using a RUVIS, exposure times need to be kept to a minimum.

My experience has been that CAE fuming semi-porous items and then spending a little time with a bright light and magnifying glass examining the item while varying the light angle, marking off the developed prints, photographically documenting the prints (using various lighting techniques) and then following up with a mag powder and re-photographing has worked well for me but as one of the posts points out, don't be afraid to do your own tests on non evidentiary items that are similar to the evidence.


Bests,

Gary

[THEO VELDERS]

Hi Sally,

Back in 1998 at the IAI conference in Little Rock, Arkansas, I have presented a paper about the development of fingerprints on semi-porous materials using cyanoacrylate and DFO. A handout was made of this paper which can be downloaded from:
http://www.bvda.com/EN/download/Velders_CA_DFO.pdf

In this handout a simple technique is described to develop fingerprints using cyanoacrylate, DFO and Gellifters.

Best regards,

Theo

[sgustavson]

Hello All,

Thanks for your advice and Theo - thank you for attaching that article. I really enjoyed reading everyones suggestions. If I get some down time I will definitely play around with different techniques. I am excited to see how well the gel lifters work.

Thanks again

-S

[THEO VELDERS]

Hi Sally,

I was wondering if you already tried the technique which was described in the article about developing fingerprints with DFO and cyanoacrylate and subsequently lifting these with a black Gellifter? Did you have any success with the technique or have you heard of others that successfully tried it?

Best regards,

Theo