Reasonable doubt

The conviction of US student Amanda Knox for the murder of her British roommate in Perugia, Italy may have been based on unreliable DNA evidence, according to new testimony by forensic experts.

During the original trial in 2007, investigators presented DNA evidence from the presumed murder weapon that played an instrumental role in Knox's conviction. Victim Meredith Kercher's DNA was supposedly present on the blade of the knife while Knox's DNA was present on the handle.

"There was starch but certainly no DNA on the blade," said Carla Vecchiotti, an expert who has been reviewing the DNA evidence.

Experts also questioned the reliability of the DNA found on a bra clasp that belonged to 21-year-old Kercher, saying that the evidence was likely contaminated. The DNA from the bra strap was used to convict Knox's Italian ex-boyfriend, Raffaele Sollecito, in connection with the murder as well.

Investigation questioned

Piero Angeloni, head of the Italian police's forensics department, defended the work of the original investigation. In a letter read before the appeals court, he argued that the veteran investigators had used world class technology and that his department had "never before" faced such criticism.

Vecchiotti said that she could not rule out that Kercher's DNA had been found on the blade during the original investigation. She concluded, however, that "on the basis of the tests we have done today there are no traces of DNA," adding that the knife had not been handled or cleaned properly during the original investigation.

In a report published last month with her colleague Stefano Conti, Vecchiotti confirmed that Knox's DNA was present on the handle.

Gruesome murder

Kercher, an exchange student from Leeds University, was found lying half naked in a pool of her own blood in the cottage she shared with the now 24-year-old Knox. Her throat had been cut. Judges concluded that the murder occurred when a sex game got out of control.

Knox and Sollecito were sentenced in 2009 to 26 and 25 years respectively in connection with the murder. Ivorian national Rudy Guede, who admitted to having sex with Kercher before she was murdered, was also convicted.

Knox's mother, Edda Mellas, told the US network CBS that her family was becoming more hopeful that her daughter would ultimately be released in light of the questions regarding the DNA evidence.

"There were huge mistakes made in the gathering of evidence and the analyzing of evidence," Mellas said.

Author: Spencer Kimball (Reuters, AFP)
Editor: Nicole Goebel