Proceedings of the 59th Annual Meeting of the American Academy of Forensic Sciences, February 19-24, 2007, San Antonio, TX. "Effect of cyanoacrylate on DNA typing of human fingerprints". "Systematic Study on STR Profiling on Blood and Saliva Traces After Visualization of Fingerprint Marks". Thaler, A., Kuchl, S., Teissl R., Rabl, W., and Parson, W. "Effects of Cyanoacrylate Fuming, Time after Recovery, and Location of Biological Material on the Recovery and Analysis of DNA from Post-Blast Pipe Bomb Fragments". Balogh, M.K., Burger, J., Bender, K., Schneider, P.M., and Alt, K.W.
#Fingerprint analysis free
If anyone tries to tell you that you can't get DNA profiles from evidence that has been processed for fingerprints, feel free to cite one or more of these articles:ġ. If both fingerprinting and DNA collections are necessary and the laboratory insists that the DNA is collected first, then try to collect DNA samples from areas that are not good for prints, like textured surfaces. This is easily done, but the analyst needs to know to do it since it is not a normal part of the DNA testing process. That shell needs to be broken to get to the DNA in the cells. For instance, superglue is the most critical to know about because it wraps the cells in an egg shell-like cocoon. It should be mentioned to the analyst/laboratory what specific type of processing was performed so that the analyst can adjust testing processes accordingly. It is recommended that stains applied by dipping be used no more than five times before being discarded, and if the item has blood or other bodily fluids, that the stain be discarded after that use. Over time, such stains will accumulate cells from numerous individuals and interfere or even compromise DNA analysis. (If you portion out less than you think that you'll need, you can portion out more later this ensures minimal loss.) Stains that are applied by dipping can rinse off cells, which can then transfer to the next item. Instead, it is recommended that a small volume of powder be portioned out for the item being examined and that any unused portion be discarded. This includes any kind of fingerprint dusting powder or stain that has been used before. Cross-contamination, on the other hand, is most likely to happen by using reagents that have been contaminated with DNA from other items of evidence. The most likely way that self-contamination can happen is if the examiner doesn't wear gloves when handling the evidence, or if the examiner touches an object (like a pen or drawer handle) that is contaminated with his or her DNA while wearing gloves (also known as "secondary contamination"). This can happen if the fingerprint examiner contaminates the evidence with his or her own DNA or with DNA from the scene and/or evidence (see " Avoiding DNA Contamination" in the " Tutorials" section).
There is ONE way that fingerprint processing can compromise DNA analysis, and that is to contaminate it with additional DNA. HOW FINGERPRINT PROCESSING CAN COMPROMISE DNA ANALYSIS In fact, whereas wiping a gun down to remove prints is quick and easy, removing enough cells to thwart DNA analysis is almost impossible. Consider a gun: The smooth and flat surfaces of the gun are the ideal areas with which to obtain comparable fingerprints, while the textured areas are the ideal areas with which to trap cells that can be analyzed for DNA. Oddly enough, surfaces that are good for fingerprints (smooth and flat) are bad for DNA (textured), and vice versa. Latent prints are processed from the oils produced on the fingers and the DNA comes from the cells left on the object by the fingers. Therefore, if fingerprints may be critical in the case, then developing them should be done prior to sampling for DNA.įingerprint processing actually helps the DNA analyst, as it tells them where the cells are. Fingerprint processing methods, unto themselves, do not interfere with DNA testing (not even cyanoacrylate fuming, also known as "superglue"), but collection of DNA samples may interfere with latent print recovery. There are some misconceptions regarding fingerprint processing methods and DNA testing, especially when it comes to low-template samples.
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