|Posted on Tuesday, December 30, 2003 - 10:25 pm: ||
It may help you feel better to know a little bit about locating prints on an object. In fact, "latent" prints developed on items are chance impressions. They are composed of oil, perspiration, or other contaminants located on the finger at the time the item is touched. If there is nothing present on the finger, a latent print may not be left even though the item was touched. And even if there was "sweat" present, the surface itself might not be an ideal receptor for holding a fingerprint. Many surfaces (like vinyl for example) are not very likely to retain useable prints because they are semi-porous. They aren't hard like glass or metal, and likewise they do not absorb and retain the sweat like paper or cardboard. And even if the "sweat" and the "surface" factors were good, the touch itself might not lead to a latent print of value. For example, if I touch a piece of glass with a sweaty finger, but I do so with a glancing, sliding motion, all that will develop on the glass is a big smear. If I twist and turn my finger as I touch an item, the "touch" factor may also prevent an identifiable fingerprint from being developed even though I touched the surface. And finally, even if the "sweat" "surface" and "touch" factors are good, "environmental" factors acting on the surface after the fact might prevent an identifiable print from being left. These include temperature, humidity, handling, and packaging. On a hot dry day, an item being handled in a sealed plastic bag is probably not ideal for development of a latent print of value. Most laboratories require items of evidence for latent print processing to be packaged in paper containers for this reason. Paper "breathes" and is much less likely to build up condensation that can destroy fingerprint evidence.
So in review, there are four basic factors as to whether identifiable latent prints will be developed on an item that HAS been touched: sweat, surface, contact, and environment. If any of these factors are not ideal, an identifiable latent print may not be developed on an item that has been touched.
To your point specifically, I have processed many vinyl money bags in my career, and have developed very VERY few prints on them. This is mostly due to the surface itself. Vinyl is a very difficult surface on which to develop impressions, even if the other 3 factors are ideal.
I hope this information helps set your mind at ease. Regards.
|Posted on Tuesday, December 30, 2003 - 09:34 pm: ||
Someone stole some items out of my house. The case is under investigation by the police. I was able to recover a vinyl money bag where some money was taken from, I immediately placed it in plastic bag. I submitted the money bag as evidence to the detective. A month later, the detective said "there is no fingerprints" in the money bag. Is the possible? I know that the money bag has at least four sets of different fingerprints on it. I feel the detective is trying to inactive my case for "lack of evidence." I am very concern. Would you please reply.
|Posted on Monday, November 11, 2002 - 06:21 am: ||
How do you know if you left a detectable print?
- You don't until you try to develop one.
....is it really possible to get a recognizable print off of these papers?
- (hypothetically) Yes, but you don't know until you try.
Sorry if this isn't the answer you wanted but it is the only one you'll get from a latent print examiner.
|Posted on Friday, November 08, 2002 - 11:03 am: ||
How do you know if you left a detectable print? If a copy of something was made by myself and taken off of a copier, folded then handed to another person and that person shows it to many other people folds and unfolds this piece of paper many times, sticking it in pockets, purses or dresser drawers even after two years is it really possible to get a recognizable print off of these papers?
|Posted on Friday, November 08, 2002 - 04:56 am: ||
If a detectable print was left in the first place it will still be there because the sweat soaks into the paper taking with it all the salts and other constituents which will be left behing when the water evaporates.
The print will still be there, however it may be so deteriorated by what has happened to the paper since that it is no use for identification.
Things like moisture, folding, contamination by another substance and other people putting new prints in the same place etc could all render the original print worthless, unrecognisable or undetectable.
As in all cases the real answer is,
"You don't know unless you try"
|Posted on Thursday, November 07, 2002 - 10:33 pm: ||
If a person touches a piece of paper, and two years pass, throughout the two years many other people touch and handle this paper, the paper has been folded many times, and even stuck in a pocket or dresser drawer, then eventually after two years been put into a plastic bag flat, will there still be identifiable prints left behind?
|Posted on Friday, August 31, 2001 - 07:18 pm: ||
Very interesting questions. I have a sneaky suspicion there are reasons you are asking the second question, but I'll answer you anyway...
With regards to several prints on top of each other, the best way to view this is like stamping several different address stamps at the same place. Of course, the lines wouldn't directly overlap, because each line is different, and each letter is different. Also, you wouldn't stamp each different address on exactly the same point, or with exactly the same pressure or angle. There may be parts of some addresses that cannot be deciphered, but then again, parts of just one address might be unreadable just from stamping it on an odd surface like a milk jug. Just because you might not be able to read certain parts doesn't necessarily mean you will get those parts mixed up with the other parts. In other words, if you carefully analyze the direction of the letters, the pressure similarities in one address, the angle of touch, etc... you will begin to associate certain letters with one address, until it is readable. Either you can reconstruct some or all of the addresses, or you cannot. There is really no danger of not being able to tell who's is who's; it's a question of being able to read through the others and follow the one you are looking at, and then doing the same with each of the other prints.
With respect to one partial latent print associating a suspect to a crime scene; that happens all the time, all over the world. There are many reasons there might only be one print. This all goes back to the many factors that affect whether or not a latent print will be left when a surface is touched. In a vehicle, surprisingly to most people, steering wheel's are not a likely place to retreive fingerprints. This is because it is constantly being touched, and the sweat and oils cover the entire surface (which is usually textured to begin with.) Many other places in vehicles are not as conducive to latent print retreival as us "Latent Print Examiners" would like. Dashboards and some other types of interior vinyl surfaces are sometimes very poor receiving surfaces for latent prints. Glass, on the other hand, is a very good receiving surface. And you are correct in your thinking; it's an odd place to touch, but it happens! (obviously.) All it takes is one touch with the right factors in place, and a latent print is left. Touching unsuitable surfaces all day long, like most fabric, etc... will not leave any prints.
Hope this answers your questions!
|Posted on Thursday, August 30, 2001 - 06:56 am: ||
IF THERE ARE 5 OR 6 DIFFERENT FINGERPRINTS FOUND ON A SURFACE,ONE ON TOP OF THE OTHER, CAN YOU BE ABSOLUTLY SURE WHO'S PRINT IS WHO,S? OR IF SOMEONE STEALS A CAR WITHOUT GLOVES, WOULD YOU SAY IT WAS LIKLEY THAT THE ONLY PLACE THEIR FINGERPRINT WOULD BE FOUND IS AT THE TOP OF THE WINDOW, ONLY HALF OF A PINKY?