CLPEX Chat Board

At the agency I formerly worked at, a veteran CSI taught me to laminate documents on which Ninhydrin prints are developed. It seemed like a good idea then and still does - the developed prints are in an airtight package and would therefore stay visible longer and the latent prints of value can be easily marked on the outside of the laminate.
Considering that no document examination needs to be done on the paper item, can anyone think of any reasons why this would not be a good idea?

I assume you photograph the developed latents before doing anything--right??

Bill

Yes, photographed and scanned on a usual basis. But there have been some occasions where I had forgotten to do so prior to the lamination yet was still able to get a good photo and scan even after the lamination.

What if you need to do further processing on the document? Like Physical Developer?

Do we know that such lamination will retard the fading of ninhydrin-developed prints? Do we know the effect of the lamination adhesive on ninhydrin over time? Is the sole purpose of the lamination to prevent oxidation, or is it to allow subsequent handling of the evidence? Since it is customary to photograph/scan any chemically developed latents, I would wonder if such lamination is cost effective and what real purpose it serves.

My experience with ninhydrin and it's analogues is that developed prints will fade if exposed to light for long periods. Laminating therefore would likely not prevent fading if still exposed to light. Someone should experiment to see if this is the case. I recommend keeping developed prints in opaque envelopes to prevent fading, rather than transparent plastic bags.

Which is why we photograph them or scan them ........

In my lab, we put ninhydrined documents into ziplock bags and press out all the air before sealing the bag, then tape across the closing for extra air blockage. This seems to slow the fading and allows late developing prints to darken. It enables easy handling and photography and leaves the paper available for subsequent exam (e.g., PD) if desired at a later date.

There's just something about laminating that is too final, as if you are destroying something of evidentiary value.

There's just something about laminating that is too final, as if you are destroying something of evidentiary value.

Thomas,
That exactly was my main concern with this question. The evidence is still there, but to remove it from the lamination could be destructive. I wanted to see if anyone has any knowledge of the integrity of the evidence coming into question or being compromised because of this.

I would have to agree that it is too destructive for the small benefit of possibly reducing fading. If you do need to process it further…perhaps with a technique not yet discovered, the lamination would prevent this. Also, what if you find out later that the document needs to go to a QD examiner, you have effectively limited what examinations he/she can perform. If it is already photographed or scanned you should be working off of those. I would go with a Ziploc with the air removed in an opaque envelope to cover all of your bases in a nondestructive manner.
PG
P.S. nice Star Wars handle.

Good points, Peter. Giggity giggity.

We had a case where ninhydrin prints were developed and when the evidence was reviewed months later for court, additional prints had developed. It could be argued by a defense expert that you might have prevented possible impressions from developing (however slight) by laminating the item. I haven't heard of any studies about the affect of ninhydin prints and their exposure to air.

You all have some very good points; I will discontinue the laminating and just use clear plastic heat-sealed bags from now on. Thank You.