DNA experts clash on Amanda Knox appeal

Amanda Knox's appeal against her conviction for the murder of British student Meredith Kercher in Italy faces a fresh challenge.

A prominent forensic scientist, whose DNA evidence helped to convict the American student and her former boyfriend, has vowed to overturn the findings of an independent report that says much of her work in the case was unreliable.

Knox returns to court in Perugia tomorrow, armed with the new forensic report, which she hopes will help lead to her being freed.

Kercher was found with her throat slit in the Perugia apartment she shared with Knox in 2007. Knox and her former boyfriend, Raffaele Sollecito, were sentenced to 26 and 25 years' respectively in 2009 for the murder. A third suspect, Rudy Guede, had already been convicted for his role in the killing.

Written by two independent experts from Rome's Sapienza University, the 145-page DNA review rubbishes the work of Patrizia Stefanoni, the police forensic scientist who found Knox's and Kercher's DNA on a kitchen knife at Sollecito's house and identified DNA belonging to Sollecito on a torn bra clasp found beside Kercher's semi-naked body.

The report claims Stefanoni ignored international DNA protocols, made basic errors and gave evidence in court that was not backed up by her laboratory work, rendering the knife and bra strap worthless as evidence.

But Stefanoni has vowed to fight back during three hearings devoted to the DNA reviews.

"I am angry about the false statements in this report and ready to come to court to highlight the past record of these experts," she said. "I am also looking into taking legal action against them.

"What international DNA protocols are they talking about? The Italian police [force] is a member of the European Network of Forensic Science Institutes, while they are not."

Both Stefanoni and one of the report's co-authors - Carla Vecchiotti - are influential figures in a restricted circle of DNA experts in Italy and are no strangers to headline-grabbing cases.

Stefanoni's work helped a British court in June convict an Italian, Daniele Restivo, of the ritualistic murder of Heather Barnett in Bournemouth in 2002. Vecchiotti has recently made the news in Italy with her work investigating a drug addict's death in police custody and the murder of a teenage girl in Puglia.

Soon after she was chosen to review Stefanoni's work on the Knox case, Vecchiotti claimed that documents had been withheld from her. The final report, co-authored with Stefano Conti, bemoans the scant detail Stefanoni used to back up her findings.

The three days of DNA hearings from tomorrow will be followed in September by final arguments, with the appeal verdict expected around September 26.

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