DNA in Knox case questioned

PERUGIA, Italy – The police official who conducted the original investigation in the Amanda Knox case defended her standards Monday, after an independent review harshly criticized the evidence used to convict the American student of murdering her British roommate.

Patrizia Stefanoni took the stand as Knox’s appeals trial resumed after the summer recess. A verdict is expected by the end of the month.

Knox and her co-defendant and one-time boyfriend, Raffaele Sollecito, were convicted in December 2009 of sexually assaulting and killing Meredith Kercher in November 2007 in the apartment that Knox and the 21-year-old Briton shared while studying in Perugia. Knox was sentenced to 26 years in prison; Sollecito to 25. Both deny wrongdoing and have appealed the verdict.

An independent review of DNA traces in the case found that much of the evidence collected in the original investigation fell below international standards and may have led to contamination of the samples. The review especially focused on some traces of DNA linking the defendants to the crime, and concluded that due to the risk of contamination and the low amounts of DNA used for the testing it was impossible to extract a genetic profile with any certainty.

In the first trial, prosecutors maintained that Knox’s DNA was found on the knife’s handle and Kercher’s DNA was found on the blade. They also say Sollecito’s DNA was found on the clasp of Kercher’s bra, mixed with the victim’s.

Carla Vecchiotti, one expert questioned Monday over the extraction of DNA profiles from the bra clasp, said the data was so mixed that a very high number of genetic profiles could be extracted, depending how one combined the data.

“I could find yours, too,” Vecchiotti told the presiding judge. “I’m there, too,” she said, adding that some data was compatible with her own DNA. She said Kercher’s profile was the only certain one.

The findings have boosted the defendants’ efforts to be cleared and gain freedom after almost four years in prison.

Stefanoni, the forensic police officer, countered some of the points made in the review, saying that DNA analyses were carried out from behind a glass wall to avoid the risk of contamination. She also said some of the standard protocols cited by the experts were published after she finished her report in May 2008.

Using some of the 119 slides she said she had prepared, she challenged the experts’ finding over DNA quantity, analysis and evidence collection techniques. Her testimony will continue today.