Post Number: 42
|Posted on Sunday, December 30, 2012 - 03:54 pm: ||
The absence of finger or palm prints from a person on a surface/item they touched does not mean they had "no fingerprints" and does not mean they were wearing gloves.
Whether or not finger or palm impressions include sufficient quantity and quality of information to enable identification to a specific person is a matter of chance.
The fact a person's fingerprints are not identified on a surface or item in no way means that person did not touch the surface, before during or after the time period when other persons may have touched the item/surface.
Typically there are many small marks or discolorations which appear on surfaces/items processed for latent prints. Often, only those marks/impressions possessing sufficient quality and quantity of detail for meaningful comparison against victim/witness/suspect impressions are recorded through photography, lifting (if dusted with powder) and/or other recording processes facilitating further analysis and comparison. The potentially "sufficient" marks are recorded and all insufficient marks are ignored insofar as additional analysis and comparison activities in the case.
Often, scientists will make note that impressions which were potentially suitable for meaningful comparison were recorded, and not document that there were many other insufficient marks/discolorations on surfaces/items. This is because insufficient marks are almost always present, and often may have been caused by touching/contact with multiple things other than fingers/palms before/during/after a crime.
Similarly, scientists examining the exterior of a car for potential impact impressions related to a hit-and-run involving a pedestrian, will annotate and photograph (or otherwise process) only those impressions/marks suitable for meaningful comparison. Attempting to document 100% of every minute impression (e.g., marks that may have been caused by leaves from a prior rainstorm, or by bugs impacting a windshield) on the exterior of a car would often be impossible, and could consume tremendous resources with no potential to prove the vehicle was NOT involved in the hit-and-run.
Because it is normally not possible to prove a specific person did NOT touch a surface/item, there is typically little or no time spent working with finger/palm impressions that are insufficient for individualization. Why waste time when it is normally impossible to prove any person did not touch something... the priority is given to those impressions which might be able to prove a person DID touch something.
Defense attorneys may argue that despite impressions deposited on a surface/item by their client, the real perpetrator(s) touched the same surface(s)/item(s) as much or more than than their client, but the real perpetrator's finger/palm impressions by chance did not develop with sufficient quantity and quality (clarity) of detail to be evaluated as potentially identifiable and photographed (or lifted, etc.).
Prosecution may explain the correlation of a surveillance camera that snaps one image every 30 seconds, and which recorded an image of only the defendant at the crime scene, even though some of the shadows or blurred objects at the edge of some photos may or may not have been due to the presence another person. Prosecution must usually admit that any number of other persons may have been present in the same location, but just not within camera view when the shutter snapped.
Of course, circumstantial evidence sometimes contributes additional valuable information, such as fingerprints from a suspect discovered in wet blood from the victim immediately after a crime, or fingerprints on a surface that did not exist before a certain date (credit card receipt), etc.
Please see the "Why didn't the police dust..." question and answer in the FAQs at www.onin.com/fp
Schelli Rothi (Unregistered Guest)
Posted From: ip68-2-74-235.ph.ph.cox.net
|Posted on Sunday, December 23, 2012 - 04:21 pm: ||
No prints were found on a gun where the person was accused of firing it last yet the prints from the other guy that handled the gun were found. Is it possible that the last person that handled the gun wouldn't have prints but the one before did? This doesn't make sense to me.
Post Number: 282
|Posted on Monday, March 03, 2008 - 11:34 am: ||
This question is answered in the FAQs at www.onin.com/fp
Julz (Unregistered Guest)
Posted From: fa.lesamoa.net
|Posted on Sunday, March 02, 2008 - 02:24 am: ||
Why do some surfaces have fingerprints on them and some don't?