In our CSI-obsessed society, we are conditioned to believe that DNA evidence is the one infallible item in a prosecutor's collection. And for good reason, because all humans (save for those like myself - identical multiples) have different coding DNA. It's true that the percentage of our own DNA different from another human being is very small, but alas that percentage spread over 3 billion basepairs is still a lot of DNA. And because we all have some DNA that is different from everyone else and technologies exist to reliably detect those differences, prosecutors around the world have been using DNA evidence as the smoking gun in criminal trials.
However, a newly published study casts a shred of doubt on the Holy Grail of crime scenes. The online abstract of the study entitled "Authentication of forensic DNA samples" details the relative ease (at least for those familiar with DNA amplification and cloning technology, which would certainly include all life science professionals) that DNA evidence can be fabricated. More details about the study can be found in this NY Times article.
It must also be noted that the leading scientist of the newly published study is a founder of Nucleix, a biotech company offering an assay that can detect between artificially synthesized and naturally synthesized DNA molecules. The science behind it is actually quite simple. Artificially synthesized DNA, like that amplified via PCR or Whole Genome Amplification, is not methylated (methylation of DNA is known to be a mechanism for regulation of genes), whereas naturally synthesized DNA is partially methylated. Thus, if you assay for methylation, you can determine whether the DNA is artificial or natural depending on whether or not it is methylated.
As scientists, we should investigate on our own anything we read in regard to science, especially when the technique we read about is used for something as serious as evidence certification for crime scenes. Nevertheless, as long as the assay actually works and is reliable, I have no reason to believe the motive of the lead author to be anything devious. It could provide an extra level of protection (or certainty, depending on the circumstances) in criminal cases in which the result literally could be a life or death decision.
As an aside, it is important to note that DNA evidence has been questioned in appropriate instances in the past. A DNA lab in Houston, Texas was found in 2003 by state auditors to have "widespread flaws in its work, including sloppy record-keeping, misinterpreted data and evidence contaminated by water from a leaky roof in the laboratory."
The advance of technology in forensics labs has been, I believe, beneficial to law enforcement and society in general. DNA evidence has been a major tool of both prosecutors and defense lawyers alike, and both groups should welcome additional technology that allows for the evidence to be taken with even more certainty, either for proving guilt or proving innocence.
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Perhaps there should just be greater accountability for forensic scientists. Any researcher knows that keeping accurate records, samples free from contamination, and reserving judgement until all possible information is known are cornerstones of good science. But unlike research, there is not always a checking mechanism for forensics--if I incorrectly publish a chemical procedure, somebody may try to reproduce it and I will be discovered. Like you said, the stakes are often higher too. Crime scene investigators and forensic researchers need to be held to something equivalent to the Hippocratic Oath, recognizing that their work requires the highest levels of ethics, responsibility, and professionalism.
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