DNA has been called "The Hand of God" and in many respects it is. Certainly the science is at the cutting edge of our technology. DNA has simplified the accurate identification of disfigured remains. Countless criminals have been imprisoned based on DNA evidence and many innocents have been released from prison, and even death row, because of DNA.
Properly performed, DNA tests are unfailingly accurate. Criminal prosecutors and juries, buoyed by exposure to crime shows such as CSI and Law and Order are convinced that DNA testing always targets the culprit. DNA strikes terror into many defense attorneys, who scurry to the prosecutor’s office to try to negotiate a plea, once they receive the dreaded report.
Even DNA evidence deserves a second look, however. A DNA report should never be the end of the case. While it is strong evidence, it is not perfect evidence. Prosecutors, defense attorneys, judges and jurors must remember that the science is only as good as the human involvement. Unfortunately, the human element is just as fallible now as it was before DNA testing came upon the scene.
In evaluating DNA, the most important action is to secure independent testing. Unless your client is independently wealthy, this may take a court order. But it is essential to preparing a defense. Independent testing will minimize or even eliminate the possibility of cross contamination, evidence manipulation or intentional falsification.
Few people know that there have been several cases of falsified DNA results. The West Virginia criminal justice system was shaken in the early 1990's when authorities discovered that Trooper Fred Zain, who was in charge of the Serology Division at the State Police Crime Laboratory was investigated for falsifying results. Zain was alleged to have overstated the strength of results and the frequency of genetic matches. He is also alleged to have misreported the frequency of genetic matches on multiple pieces of evidence and reported that multiple items had been tested, when only a single item had been tested. Inconclusive results were reported as conclusive. Records were supposedly altered and the lab failed to report conflicting results or to conduct additional testing to resolve conflicting results. See, Matter of Investigation of West Virginia State Police Crime Laboratory, Serology Div. 438 S.E.2d 501, 503 (W.Va.,1993). After ascertaining that irregularities were systematic rather than inadvertent, the courts ordered new trials for a number of people convicted on Zain’s testimony.
A similar situation occurred a decade later at the United States Army Criminal identification Laboratory at Forest Park Georgia. Serologist Phillip Mills was also accused of falsifying results as well as allowing cross-contamination. The Court of Appeals for the Armed Forces ruled that Mills’ actions triggered the requirement for a hearing to determine whether or not a new trial should be ordered. United States v. Luke, 63 M.J. 60 (C.A.A.F. 2006). In another case the Judge Advocate General of the Navy set aside the conviction of a Naval Officer which was based on Mills’ testimony. In this case a re-test exonerated the officer. See, http://www.mcclatchydc.com/military-injustice .
The wise defense attorney does not rely on the report alone but demands the laboratory notes, protocols, calibration records and audits of the laboratory. The laboratory notes may reveal discrepancies in the examiner’s testimony and the raw results on the strength of the reading and number of matching loci may provide fertile grounds for cross-examination. Protocols and the adherence thereto may give rise to questions of cross-contamination.
The type of DNA discovered is also important. Obviously semen or blood is strong evidence, but epithelial cells (skin cells) could be less damning evidence. Skin cells are passed by a handshake or a head scratch and are routinely left by everyone in their travels. If the defendant had been at the crime scene prior to or even after the crime, for a benign purpose, the impact of the epithelial cells can be diminished. Additionally, do not underestimate the effect of cross-contamination. Remember that many deaths in the anthrax attacks came from cross-contamination at Post Offices. The same type of cross-contamination can occur at crime scenes and in the lab.
DNA evidence is evidence. Like all evidence it must be examined and evaluated. Like other evidence it has its strengths and weaknesses and those need to be investigated. DNA can only be introduced through the testimony of an expert. That expert is subject to cross-examination. Independent investigation, analysis and good lawyering can shake DNA evidence and possibly keep an innocent person from being convicted.