Will Errors Plague a Plan to Process a Huge Backlog of Detroit DNA Evidence?

News recently emerged that over 10,000 long-ignored rape kits will soon receive the attention of a Michigan State University study. The evidence has been in storage since April 2008, when authorities shut down the Detroit Police crime laboratory because of its history of mishandling evidence. The Michigan State Police, which has been handling Detroit evidence since the shutdown of the DPD operation, intends to pay private labs to analyze 400 randomly selected rape kits, and this data will supposedly provide a basis for MSU researchers to assess how long it will take to process kits from the thousands of other sexual assault cases collecting dust in storage trailers. Previous estimates calculated that it would require well over two years and as much as $15 million to engage private companies to assess this evidence, some of which dates back to the mid-1990s.

The use of DNA evidence to establish the identity of criminal suspects generally gets a free pass in the media, and the public's infatuation with a host of criminal forensics television dramas has created challenges for defense attorneys who must establish reasonable doubt in the minds of jury members.

Detailed critiques of the technical shortcomings of DNA testing are one viable criminal defense strategy, but reports of systemic problems in evidence processing like those that plagued the DPD lab before it was shuttered also deserve broader attention. One example worth recalling is the Illinois State Police's 2005 cancellation of a contract with the Bode Technology Group after the private lab's DNA analysis was found to have failed in a shocking 22 percent of cases when reviewed by Illinois state forensic scientists.

Scrutinizing results to hold prosecutors to their burden of proof

Defense lawyers employ a variety of challenges to attack the validity of DNA evidence. Depending on the circumstances of a particular case, evidence can be challenged based on:

  • Errors during handling of samples: Far too often labs mislabel or cross-contaminate biological samples, particularly when reference samples and evidence samples are handled in close proximity. Such mix ups obviously produce false results.
  • Establishing exactly what was tested: The lab must be able to show exactly what was used to produce a DNA result - semen, skin cells, blood or saliva, for example. Surprisingly, lab results often fail to disclose basic information about the substance that was scrutinized.
  • Questioning how the sample got there: DNA tests are extremely sensitive, and miniscule samples can contain enough cells to produce incriminating results. But this extreme sensitivity also means that inadvertent DNA transfers can easily lead to erroneous conclusions and overzealous prosecution of innocent people.
  • Misinterpretation of test results: Contrary to popular opinion, DNA tests do not produce foolproof data in every case. Sometimes lab analysts must make subjective judgments to finalize results. Discrepancies between DNA profiles that were identified as having a common source are a warning sign. Close scrutiny of underlying electronic data may uncover discrepancies that prosecutors failed to disclose.
  • Exaggeration of statistics: Controversy over statistical characterizations of DNA test results continues to grow. When a test involves mixed samples or incomplete profile matches, forensics labs tend to present statistics in ways that may unfairly work against the accused, such as emphasizing the match of a single marker that the majority of people in the general population have.

The testimony and analysis of expert defense witnesses can play an important role in cases involving DNA evidence. Because of the many complex evidence issues presented in felony sexual assault cases, a criminal defense attorney with experience attacking DNA evidence is a crucial asset.

A pending wave of future prosecutions

Michigan's plan to process such a vast backlog of evidence has all the marks of a classic rush to judgment, and the likelihood of a significant number of resulting errors that lead to false arrests is difficult to underestimate. People who find themselves caught up in this dragnet can find clear answers about their rights and legal options by consulting with a lawyer.


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