DNA evidence in Knox case is valid, argues police expert

AN ITALIAN forensic police expert — who conducted the original investigation in the case of American college student Amanda Knox — insists there was no contamination on crucial pieces of evidence linking Knox and her co-defendant to the murder of her British roommate.

Patrizia Stefanoni examined DNA traces in the aftermath of the 2007 Meredith Kercher killing.

But her work was criticised by the court-appointed experts who have alleged glaring errors in evidence gathering and possible contamination, including on a knife considered to be the murder weapon.

Stefanoni told an appeals court yesterday that she could rule out contamination on the knife, which she insists contained Kercher’s genetic profile.

Patrizia Stefanoni was on the stand for two days as Knox’s appeals trial resumed after the summer recess.

A verdict is expected by the end of the month.

Knox and her one-time boyfriend and co-defendant, Raffaele Sollecito, were convicted of sexually assaulting and killing Ms Kercher in the apartment Knox and the 21-year-old Briton shared while studying in Perugia.

Knox was sentenced to 26 years in prison and Sollecito to 25.

Both deny wrongdoing and have appealed the December 29 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 a 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 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 this week 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.

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