The strange case of Amanda Knox, the 23-year-old American convicted in 2009 of killing her roommate in Italy and sentenced to 26 years in prison, may get new life. Independent forensic experts issued a report on Wednesday casting doubt on the key forensic evidence used to convict Knox and her ex-boyfriend, Raffaele Sollecito.


In case you've forgotten this sensational trial, the two were accused of killing Meredith Kercher, a British exchange student, in 2007 during sex play that went out of control, according to Italian prosecutors. The case hinged on a knife found in Sollecito's kitchen drawer, which prosecutors said had traces of the victim's blood on the blade and DNA from Knox on the handle. Kercher's bra clasp, found on the floor of the bedroom, was said to have DNA from Sollecito.


The new forensics report, issued to the appeals court through which Knox and Sollecito are trying to overturn their convictions, states that testing of the DNA was below international standards and was improperly handled and became contaminated. Predictably, the defense has claimed that the report by itself will destroy the case against Knox and Sollecito, and prosecutors say that the defense is overplaying the matter. As The New York Times puts it :


Other accusers of Ms. Knox and Mr. Sollecito said that the DNA was just one piece of evidence in the case that they built against them, based on various testimonies, their lack of an alibi and what prosecutors say is other damaging physical evidence, which has not been reviewed. During one interrogation, Ms. Knox allowed that she was in the house when Ms. Kercher was murdered, an admission she later retracted, saying she had spoken under duress.


Given the lack of a clear motive and eyewitnesses other than the defendants, the defense may have a strong case, especially if the CSI effect is real. The idea is that, because of the popular television show (which has an Italian version), jurors demand forensic evidence and value it over other kinds of evidence. Forensic anthropologist Max M. Houck, director of West Virginia University’s Forensic Science Initiative, recounted some possible examples in his July 2006 Scientific American article on the subject:


The press started to pay attention to the issue in 2003, collecting anecdotes from attorneys and judges about what appeared to be a change in the behavior of jurors. In 2005 Oregon district attorney Josh Marquis, vice president of the National District Attorneys Association, told CBS News, “Jurors now expect us to have a DNA test for just about every case. They expect us to have the most advanced technology possible, and they expect it to look like it does on television.” Indeed, jurors in a Los Angeles murder case complained that a bloody coat had not been tested for DNA, even though such tests were unnecessary: the defendant had already admitted to having been at the crime scene. The judge noted that TV had taught jurors about DNA tests but not about when they should be used. In a study in Delaware of how juries deal with evidence, one juror tangling with a complex DNA case complained that these kinds of problems did not happen “on CSI.


Attorneys blamed the CSI effect when a Baltimore jury acquitted a man of murder—testimony from two eyewitnesses was trumped by a lack of physical evidence. “I’ve seen a big change in jurors and what they expect over the last five years,” defense attorney Joseph Levin of Atlantic City, N.J., told a local newspaper. “Jurors can ask questions of the judge while in deliberations, and they’re asking about what they see as missing evidence. They want to know where the fingerprints are or the DNA. If it’s not there, they want to know why.” In the California murder trial of actor Robert Blake, prosecutors tried to persuade the jury by establishing Blake’s motive and opportunity, and they presented witnesses who testified that Blake asked them to kill his wife. But no gunshot residue or blood spatter evidence was presented, and Blake was acquitted. A juror was quoted as saying that if the prosecutor “had all that information, that would have meant [Blake] was guilty.” The defeat was the prosecutor’s first in 50 murder cases.


Although lawyers believe that a CSI effect is at play, others have their doubts:


What appears to be the first study of the CSI effect was published in February by Kimberlianne Podlas, an attorney and assistant professor of media law and ethics at the University of North Carolina at Greensboro. Podlas concluded that the chances of, and reasoning for, acquittals were the same for frequent CSI viewers as for prospective jurors who did not watch the show—she saw no CSI effect. Several participants, however, said that a lack of forensic testing was an issue, despite the fact that physical evidence would not have resolved the hypothetical charges. Studies of real juries have been advocated, and at least five graduate students (three in the U.S. and two in England) are preparing theses examining the effect.


Whether or not forensics shows are measurably influencing the demands and decisions of juries, television is unquestionably giving the public a distorted view of how forensic science is carried out and what it can and cannot do.


You can listen to the Science Talk podcast interview with Houck (or read the transcript) or purchase the issue with the article here.


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