CLPEX Chat Board

I have a case (Steve Buzzword = 1 point) that is from 1986. There are ninhydrin prints (NOT first processed with DFO) that according to the notes were compared as late as 1993. The problem is that they have since faded and are no longer visible. There are no photographs in the case (pffft old timers...), so my question is what would you do to 'refresh' the prints?

Not much literature on the subject that I could find other than this (http://www.jstor.org/pss/1142254) and this (http://www.ncbi.nlm.nih.gov/pubmed/3711825) and I'll have to wait until tomorrow to get a copy from my buddy with a university login to see the full text, but the second article mentions lasers so I'm pretty much counting that one out. Unless....... *makes 'pew' 'pew' laser noises*

My lab options are DFO, NIN, PD and Indanedione if that helps. Just thinking out loud here, but my first thought would just be to re-NIN it, however for some reason that just seems too obvious.

thanks in advance,

Boyd

Boyd,

You may have already attempted this type of enhancement, but this may have some guidance:

“Restoring Faded Authentiprint Fingerprint Image on a Check”, Ricard Tomboc, JFI 55:2 (2005)
Comment: Using an ALS (Omnichrome 1000) to enhance faded fingerprint

Ernie

Thanks Ernie. For anyone interested, the article including pictures can be found online here: http://www.crime-scene-investigator.net ... print.html

After brainstorming and talking with some people in the office, I've come up with the following:

Non Destructive:

IR photography
ALS
Re-Heat/Re-Steam

Chemical:

Indirect NIN (place the item in a bag with another NIN soaked paper and let it absorb the fumes)
Direct NIN
Indanedione (although that's just a NIN analogue, so.....)
PD
Zinc Chloride. (I'd have to check to see if we have that)


If anyone wants to provide feedback on these ideas, feel free.

Also, for what it's worth, the paper is a carbonless copy of a receipt.

I had pretty good results with the ALS. My order of preference were

CSS + Orange Barrier Filter
415 + Yellow Filter
575 + Red Filter

I also tried some UV photography with an 18A filter and I some poor man's IR by combining the 25 and 58 filters. Both produced no noticeable ridges.

For those who aren't familiar with the CSS setting, it stands for Crime Scene Search is a shortpass 540nm. We use a Crimescope CS-16-500.

A technique that may work on faded Ninhydrin prints is through the use of a desktop scanner. If the interface provides a Gamma control, bump it up & check the results (a setting of 1.0 to 2.0 is often the default setting; try doubling that). Depending on your hardware/software combination, the Ninhydrin prints may become much darker, hopefully leaving the background white, or close to it. And it's non-destructive.

There are many variations of this effect. I had an old, inexpensive Visioneer scanner that seemed to work miracles with ninhydrin prints, often making latent prints that could not be seen with the naked eye visible, & with good contrast.
Regards, RLT

Just another thought, I've been able to get some decent contrast on faint Ninhydrin prints by photographing/scanning (your preference) the print then using the lab color/alpha channel in Photoshop. Sometimes it really brings out the ridges....

Andy

Hi Boyd,

Someone you may have met and who has recently retired was our principal research scientist and physicist Milutin Stoilovic the inventor of the Polilight. His recommendation is Zinc post treatment, with liquid nitrogen cooling and viewed in photoluminescence mode. If no improvement then PD. His strong advice is not to retreat with Ninhydrin.

I agree that the optical techniques being non destructive would precede the chemical techniques.

Cheers from oz. les

Hi Les
toally agree
Further ninhydrin tends to increase background staining.