Wednesday, June 13, 2007

Shoddy Forensic Science Injures Real People's Lives

Harris County DA Chuck Rosenthal may oppose a special master for the Houston PD crime lab, but I'll bet these three fellows wouldn't object.

The final report of the Houston PD Crime Lab's Indepdent Investigator includes numerous case studies where shoddy forensic science and overstated conclusions led to unjust outcomes for defendants. Here are three telling individual examples from the report (pp. 14-15):

Lawrence Napper
The Napper case relates to the 2001 kidnapping and sexual assault of a young boy in which the Crime Lab analyzed samples taken from the outside of the victim’s cheeks that the Lab found contained semen. Although the Crime Lab’s original DNA testing appears to have generated good quality and clear results from potentially very difficult forensic evidence samples, the Napper case illustrates two significant problems with the Lab’s historical DNA work. First, Crime Lab analysts utilized all of the readily testable sample in this case, which was unnecessary and was the product of very poor laboratory practice. Second, the written conclusion and testimony of the Crime Lab analyst that the mixture profile he found in the “face-cheek” swabs “statistically matches” Mr. Napper is internally contradictory and completely inappropriate. The analyst’s report and testimony almost assuredly created the impression with jurors that Mr. Napper was the only person on earth who could have contributed the DNA taken from the victim’s face, which is a conclusion not supported by his actual DNA results.

George Rodriguez
George Rodriguez was wrongfully convicted of the 1987 kidnapping and sexual assault of a 14-year-old girl, a crime for which he served nearly 17 years in prison before being released in 2004. Flawed serology work and testimony were central to Mr. Rodriguez’s conviction. Based on seriously problematic serology analysis, the Crime Lab incorrectly excluded a key suspect whom investigative leads and Mr. Rodriguez’s defense pointed to as the likely real perpetrator. While the Crime Lab was not incorrect in finding that its serology analysis could not eliminate Mr. Rodriguez as a potential contributor to the biological evidence, it provided no information regarding the significance of Mr. Rodriguez’s inclusion -- which was minimal because most of the male population could not be eliminated as a potential contributor to the evidence in this case based merely on ABO typing.

Josiah Sutton
Josiah Sutton was released from incarceration on March 12, 2003 after serving four and a half years of a 25-year prison sentence for a sexual assault that he did not commit. The Sutton case in many respects is a microcosm of the range of problems we observed during this investigation related to the use of forensic DNA evidence in the Harris County criminal justice system. The system failed at multiple points, with the result that Mr. Sutton was wrongfully convicted based largely on flawed and misleading DNA work. As a result of poor technique and lack of training, the Crime Lab analyst, using PCR testing, produced ambiguous results reflecting complex mixtures, the interpretation of which was very difficult. The problem was exacerbated by the Crime Lab’s practice, followed by the analyst in this case, of failing to accurately convey the significance of the associations they found between suspects and evidence through DNA testing, particularly in mixture cases. Nearly eight years after the crime, the proper use of forensic DNA testing led to a CODIS hit and the conviction of the actual perpetrator.

No comments: