DNA Evidence on Trial

DNA has transformed the field of forensic sciences, yet ever since its first use in a criminal investigation in 1987, the evidence has proven only as reliable as those doing the testing. In that first case, DNA evidence aided in the conviction of Colin Pitchfork for a double rape and murder in Narborough, England. Using blood samples of the town's residents, the crime lab originally ruled out Pitchfork, who had asked a coworker to submit a blood sample for him. By happenstance, someone overheard Pitchfork's friend talking about the switch. Pitchfork eventually confessed to his crime, and DNA testing proved his guilt.1 Almost 20 years later, the quality of DNA testing has improved, but problems are still evident. Lab mistakes that have sent the innocent to prison as well as freed the guilty have prompted law-enforcement experts to call for standardization and accreditation. Standardization is particularly important, they say, in light of the volume of DNA samples awaiting analysis in crime labs. The National Institute of Justice estimates that law enforcement has failed to examine as many as 350,000 DNA samples from homicide and rape cases. US Attorney General John Ashcroft proposed committing $1 billion (US) over the next five years to help clear the backlog, keep labs up to date, and expand the national DNA database. TIGHTENING THE TESTS Before labs can put this money to use, many will need to reform their testing procedures. The Houston Police Department (HPD) recently came under fire when an investigative news report documented seven convictions featuring shoddy DNA testing, including that of a man wrongly convicted of rape who had served four years of a 25-year sentence. An audit of the department found that evidence was routinely mishandled and protocol unheeded. The HPD's crime lab was shut down in January. Now Marie Munier, assistant district attorney and chief of the trial bureau at the Harris County Attorney's Office in Texas, is reviewing HPD police reports in which DNA exculpated defendants from 1992 onward, and has so far identified nearly 200 cases. The city of Houston funds the retesting, which is being done at Identigene, a local lab. "We identify which of those investigations has resulted in the filing of criminal chargers," Munier says, "and from those, one of our prosecutors reviews [them], looking to see if DNA testing was actually done on the cases." The Texas House of Representatives passed a bill on May 1 requiring the accreditation of crime labs. By Sept. 1, forensic evidence from unaccredited labs in the state will be banned all together. "There's been continually increasing pressure brought to bear by employers to become certified," says Peter Barnett, chairman of the examination committee of the American Board of Criminalistics (ABC) and an author of the certification test. "But [usually] there's no legal requirement and/or employment requirement, so there's simply no reason for people to put effort into it." ABC offers a written examination for the certification of forensic scientists. To become certified as a fellow, a candidate takes a three-hour exam, which broadly covers the forensic sciences and law. The exam also covers forensic serology and molecular biology as they apply to DNA analysis, detection of blood, and identification of biological materials. Only New York, Oklahoma, and Texas require accreditation for crime labs. Because the process is both a time- and dollar-intensive procedure, most labs opt not to do it. Forensic science has a long history of independence, and accreditation is not highly regarded by those in the field, says Mike Haas, registrar for the ABC. "Many forensic scientists have been in this field for a while, and often they feel they don't need the certification ... [because] they have to prove their expertise in trials anyway," says Haas. According to the American Society of Crime Laboratory Directors/Laboratory Accreditation Board (ASCLAD/LAB) in Garner, NC, of the 400 to 500 labs performing forensic work, 240 are fully accredited and 25 currently are seeking accreditation. Ralph Keaton, executive director of ASCLD-LAB, says the process of attaining laboratory accreditation includes examinations for proficiency testing, testimony monitoring, documentation, and validation of procedures and of the physical lab. A lot of work for something not mandatory, but in light of recent events, Caroline Caskey, president of Identigene, would not have it any other way. "I think all labs should require accreditation," she says. "I think what happened in Houston and in other places is a testament to that." Hal Cohen can be contacted at hcohen@the-scientist.com. 1. H.C. Lee, F. Tinardy, Blood Evidence, Cambridge, Mass.: Perseus Publishing, 2003. function sendData() { document.frm.pathName.value = location.pathname; result = false if (document.frm.score[0].checked) result = true; if (document.frm.score[1].checked) result = true; if (document.frm.score[2].checked) result = true; if (document.frm.score[3].checked) result = true; if (document.frm.score[4].checked) result = true; if (!result) alert("Please select") return result; } .myradio{background-color : #94bee5} Please indicate on a 1 - 5 scale how strongly you would recommend this article to your colleagues? Not recommended 1 2 3 4 5 Highly recommended Please register your vote

DNA Evidence on Trial

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