latent prints in blood

[Julie]

I have come across a case in which it appears that latent prints that are deposited in blood (dried) do not develop well with latent print powders. Obviously, when one has a latent in blood, the preferred method would be blood chemistry enhancement. But in this case, the processor used powder and developed a print. The interesting thing is that the more obvious blood droplets surrounding the latent seemed to repel the latent print powder, but the powder adhered to the latent print with no problem - the latent was not visible prior to processing, and the processors claim that the latent is in blood. I have since asked around and found another person who said that they observed that dried blood doesn't attract latent print powders well in their experience. I'm interested in any other experiences out there and if there are any articles on this subject. This case hinges on a supposedly "bloody" print that was never tested as blood and at least appears to be a "standard" residue print as opposed to blood. What have you all experienced?

[Royce D. Wilson]

Julie...it surprises me that the "processors" can say that the latent print residue was blood, based on the information that you provided in that the print was not visible (although this is possible to a degree in blood prints)and was not developed with a blood enhancement technique, but rather what sounds like conventional black powder, and it also sounds like the print residue was never tested to see if it was blood. The latter point being a critical step, even if the print was visible and appeared to be blood.
That is quite a leap to now say with certainty that the latent was a blood residue deposited latent.
A good resource on the subject is the Processing Guide for Developing Latent Prints, published by the DOJ / FBI. I don't recall the website, but you can Google latent print processing techniques, and the website will come up in the responses.
Good Luck on that, Royce

[Julie]

Royce, thank you so much for your reply.

In retrospect, I should have just simply asked "has anyone had any experiences processing bloody prints with powders?" as I think my posting confused people and made them think I had ulterior motives (which, I don't).

I totally agree with your comments and have found this to be a big issue in this case. Unfortunately, I think I confused everyone (because of the length and background information) with my posting and/or offended them because I said "obviously" the preferred method would be blood chemistry. . .my intent with that was to show that powder might not be the preferred method, but that's what was used in this case. I'm actually not questioning the processors for using powder. Before this came up, I would have thought powder would still be effective (if not the preferred method). . .but, I'm finding that it actually doesn't seem to adhere very well to bloody prints and I was just curious what others had observed. My intent was not really to attack the processors' method (again, I would have thought it would work just fine), but rather to see if there is any research out there on powder and bloody impressions. Realistically, there is likely to be "standard" residue in a bloody print, too - and powder would hopefully adhere to that - but at what point does the "blood" factor take over and cause the powder to NOT adhere?

You are totally right, I do think the processors are wrong for calling it "blood" without testing it - and that's an important but separate issue to what I was (poorly) trying to ask and an issue the defense attorneys will have to address.

Here I go with another long and confusing posting!

Anyway, I really do appreciate your response (I was feeling alone out there )

Julie

[Charles Parker]

Julie--the following case happened a number of years ago probably about 1983 or 1984. There was a triple murder of a family and the following day some evidence was found in a dumpster. One piece of this evidence was a soda can with a patent print that was consistent with blood (visible, red, wet appearance, filled in areas where there was too much material, etc.). For whatever reason the CSO at the time did not photograph it but powdered it with regular black powder and made a lift. Taking most of the material with it. This was later identified with the suspect. No DNA back then but a sample from the edge of print indicated it was blood and of the same type as one of the victims (husband). The case went to trial and he was found guilty. About 10-12 years later it was on appeal and one of the contentions was that the proper technique was not used on the blood print and testimony concerning it should not be allowed.

Back then that agency did not have or even know about Amido or any other blood enhancement technique.

The conviction was affirmed and from my memory the powder adhered fine but this was a fairly recent blood print (1 day) and there was no difficulty in identifying it to the subject. The expert for the appeal never contested the identification just that the method to obtain it was not proper.

I do not know if this helps you but it is the only blood print in my memory that was developed using powder. Before that they were just photographed.

Sometime between the time the patent print was processed with powder and the appeals that agency became aware of Amido Black and begin using it.

This case sticks in my memory because of who the defense expert was, but that is another story.

[Julie]

Charles, thanks so much - sounds like an interesting case with some even more interesting stories Thanks for the experience - I'm getting ready to try to experiment with this concept and any "tidbits" will help with the design of the experiment (and perhaps help me to not waste too much time on "re-inventing the wheel" if that be the case

Thanks again
Julie

[RL Tavernaro]

Julie,
Time, substrate, pressure and environmental variables can all play a part in determining adherance characteristics of the latent residue.

I have had many cases in the past (both pre & post blood enhancement chemistry availability) with partial bloodprints being 'enhanced' by the application of powder. My recollection is that sometimes the powder would adhere to the existing partial bloodprint, sometimes not; but often, previously non-visible portions of the latent would be developed with the powder. Many times this was the difference in the print being identifiable.

A similar 'trick' on porous surfaces was the application of ninhydrin, which could turn a latent print with otherwise insufficient detail into an identifiable print.

Close observation of the entire visible/developed print (use of a microscope may be helpful in some cases) should reveal if the 'enhanced' portion of the print is indeed an extension of the visible portion, or represents a print that was desposited separately.

Regards, RLT

[areitnau]

I would think the application of powder would be beneficial if the matrix of the latent (being the blood) was not 100% dried to allow the powder to adhere to the residue. I've only been in the field of latent processing for a year and a half, but I have always had the best results using chemistry, light, and high-end photography to enhance and capture a latent. So far, I have tried to steer field personnel from powdering items when our chemical enhancement techniques can yield a better result. As for trying to enhance a latent that has been previously powdered, I have had some success using compressed air (such as for a PC keyboard) to blow away the powder then attemp chemical techniques.

Andy