CLPEX Chat Board

I have to give a 30-45 minute presentation to a group of Fire Investigators and was looking to discuss a few of the questions the person running the class was interested in including in the talk:

1. Which processing techniques generally work best on charred items
2. How to package charred paper
3. How to package Molotov cocktails (provided the wick or liquid was removed for ignitable liquid testing)
4. How to package tape removed from something
5. The possibility/likelihood of getting latent prints from matches
6. The effect (if any) that heat, petroleum products, acids and bases have on fingerprints

I already have thoughts on most of these, but would like to have others input as well. Also, if you happen to know of any relevant articles, and where to find that that would be helpful.
Thanks
PG

Peter,

Two suggestions:

Go to www.redwop.com (Yes, the old website for Lightning Powder Company which is still active), click on “Minutiae” tab and view issues #77 and #79.

Link to “Hamm’s Fingerprint Index” from CPLEX home page and enter “arson” as search query. There will be a number of articles on the subject, but also some unrelated because, “arson”, is just part of an author’s name.

Ernie

thanks!
PG

Peter,

Another technique we've noticed, specifically dealing with partial soot on glass (i.e. remnants of molitov cocktails) or metal surfaces is to obtain some solid camphor and place it in a spoon (you don't need much, about a cubic centimeter of it). Light the camphor and it will produce a dark black smoke. Place the item in question about 5 inches or so above the smoke and coat the object in soot. Once the item is covered in soot, take a brush (regular print brush) and without any powder, just lightly dust over the area and you will see that the soot actually sticks to the friction ridge detail and the brush removes it from the furrows. This works especially well on paint cans and I think we've also had some success on galvanized metal surfaces too.

The soot phenomenon as described by JRClark is a long-standing development technique (sometimes substituting masking tape or pine tar as the source for the soot production). Perhaps of interest for this thread, the phenomenon may also be produced naturally at a fire scene.

If there are items/surfaces covered with a fine layer of black soot, there may be latent prints hidden away, waiting to be revealed by merely brushing away excess soot. As an alternative method that may be effective in instances where the soot is more firmly attached to the surface, a gentle stream of water may wash away excess soot, revealing a latent print outlined in soot 'bonded' to the surface. I have successfully developed latent prints using both methods, however not in large quantities.
Regards, RLT