Abstract

Shoe prints and finger prints placed in blood on non-porous substrates are usually treated with chemical means to achieve a better contrast of the blood traces on the carrier material. The subject of this research was to explore the possibilities to improve visualization of blood traces, after they were detected with Luminol, by exposing them to other chemicals, such as Leuco Crystal Violet (LCV), Acid Yellow 7 and/or Hungarian Red.

This research led to some very interesting results, which shows that LCV appears to be a less suitable chemical to improve this visibility on non-porous substrates.

Looking for answers

See for example the traces on Photos 1 and 2. I will further discuss the traces shown in Photo 1 and 2 later in this article.

What did not become entirely clear was how one had arrived at the conclusion that LCV is a good enhancement reagent for shoeprints and fingerprints in blood on non-porous surfaces. I suspect that this conclusion was fed by the simplicity using the product.

My questions therefore were:

• In what way did one establish that a blood trace treated with LCV has shown all the latent information that may have been present in a trace?


• Did one subsequently treat the blood trace treated with LVC with another chemical product, in order to verify whether all the latent information in the trace had been developed?

It probably has not been done, as it was not done in the CHEMZIS research: once a blood trace was treated with a chemical reagent or staining solution, the same trace was not used again to look for a possible enhancement with a different reagent or staining solution.

In the past I made this same mistake myself and failed to look for a possible enhancement of a blood trace already treated, even though this was standard procedure with latent fingerprints, using, for instance 5-MTN after having used DFO. I never thought that this would also be possible with blood traces.

< read the complete article and view example photographs >

• Developing DNA Friendly Fluorogenic Methods for Detecting, Enhancing, and Preserving Bloody and Proteinaceous Impression Evidence, Jodi Lynn Barta, Ph.D., Wilson Muse III, Ph.D., Jessica Zarate, M.S.
• Latent Blood Prints — Methods For Chemical Enhancement, Don Penven
• Guide for the Chemical Enhancement of Bloody Footwear and Tire Impression Evidence, SWGTREAD