Effect of Fingerprint Processing on DNA Analysis
There are some misconceptions regarding fingerprint processing methods and DNA testing, especially when it comes to low-template samples. 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. Therefore, if fingerprints may be critical in the case, then developing them should be done prior to sampling for DNA.
FINGERPRINTS AND DNA CAN COEXIST
Fingerprint processing actually helps the DNA analyst, as it tells them where the cells are. 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. Oddly enough, surfaces that are good for fingerprints (smooth and flat) are bad for DNA (textured), and vice versa. 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. In fact, whereas wiping a gun down to remove prints is quick and easy, removing enough cells to thwart DNA analysis is almost impossible.
HOW FINGERPRINT PROCESSING CAN COMPROMISE DNA ANALYSIS
There is ONE way that fingerprint processing can compromise DNA analysis, and that is to contaminate it with additional DNA. 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). 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"). 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. This includes any kind of fingerprint dusting powder or stain that has been used before. 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. (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. Over time, such stains will accumulate cells from numerous individuals and interfere or even compromise DNA analysis. 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.
It should be mentioned to the analyst/laboratory what specific type of processing was performed so that the analyst can adjust testing processes accordingly. For instance, superglue is the most critical to know about because it wraps the cells in an egg shell-like cocoon. That shell needs to be broken to get to the DNA in the cells. 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.
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.
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:
1. Balogh, M.K., Burger, J., Bender, K., Schneider, P.M., and Alt, K.W. "Fingerprints from Fingerprints". International Congress Service 2003;1239:953-957.
2. Bille, T.W., Cromartie, C., and Farr, M. "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". Journal of Forensic Science 2009; 54(5):1059-1067.
3. Grubwieser, P.. Thaler, A., Kuchl, S., Teissl R., Rabl, W., and Parson, W. "Systematic Study on STR Profiling on Blood and Saliva Traces After Visualization of Fingerprint Marks". Journal of Forensic Science 2003; 48(4):733-741.
4. Pitilertpanya, S., and Palmbach, T. "Effect of cyanoacrylate on DNA typing of human fingerprints". Proceedings of the 59th Annual Meeting of the American Academy of Forensic Sciences, February 19-24, 2007, San Antonio, TX. Colorado Springs, CO: American Academy of Forensic Sciences, 2007.
5. Van Oorschot, R.A.H., and Jones, M.K. "DNA fingerprints from fingerprints". Nature 1997; 387:767.
FINGERPRINTS AND DNA CAN COEXIST
Fingerprint processing actually helps the DNA analyst, as it tells them where the cells are. 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. Oddly enough, surfaces that are good for fingerprints (smooth and flat) are bad for DNA (textured), and vice versa. 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. In fact, whereas wiping a gun down to remove prints is quick and easy, removing enough cells to thwart DNA analysis is almost impossible.
HOW FINGERPRINT PROCESSING CAN COMPROMISE DNA ANALYSIS
There is ONE way that fingerprint processing can compromise DNA analysis, and that is to contaminate it with additional DNA. 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). 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"). 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. This includes any kind of fingerprint dusting powder or stain that has been used before. 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. (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. Over time, such stains will accumulate cells from numerous individuals and interfere or even compromise DNA analysis. 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.
It should be mentioned to the analyst/laboratory what specific type of processing was performed so that the analyst can adjust testing processes accordingly. For instance, superglue is the most critical to know about because it wraps the cells in an egg shell-like cocoon. That shell needs to be broken to get to the DNA in the cells. 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.
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.
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:
1. Balogh, M.K., Burger, J., Bender, K., Schneider, P.M., and Alt, K.W. "Fingerprints from Fingerprints". International Congress Service 2003;1239:953-957.
2. Bille, T.W., Cromartie, C., and Farr, M. "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". Journal of Forensic Science 2009; 54(5):1059-1067.
3. Grubwieser, P.. Thaler, A., Kuchl, S., Teissl R., Rabl, W., and Parson, W. "Systematic Study on STR Profiling on Blood and Saliva Traces After Visualization of Fingerprint Marks". Journal of Forensic Science 2003; 48(4):733-741.
4. Pitilertpanya, S., and Palmbach, T. "Effect of cyanoacrylate on DNA typing of human fingerprints". Proceedings of the 59th Annual Meeting of the American Academy of Forensic Sciences, February 19-24, 2007, San Antonio, TX. Colorado Springs, CO: American Academy of Forensic Sciences, 2007.
5. Van Oorschot, R.A.H., and Jones, M.K. "DNA fingerprints from fingerprints". Nature 1997; 387:767.