ROME (AP) - Experts dispute much of the forensic evidence collected against Amanda Knox, saying in a report Wednesday that testing of DNA traces used to convict the American student and her co-defendant in the murder of her roommate was below international standards and evidence may have been contaminated.
The review by two court-appointed independent experts was requested by the defense and had been eagerly awaited. Its conclusions will undoubtedly boost Knox's chances of overturning her murder conviction.
Knox was convicted in 2009 of sexually assaulting and murdering British student Meredith Kercher - with whom she shared an apartment while both were exchange students in Perugia - and sentenced to 26 years in prison. Her co-defendant and ex-boyfriend Raffaele Sollecito was also convicted and sentenced to 25 years.
Both have denied wrongdoing and are appealing.
Prosecutors maintained in the first trial that Knox's DNA was found on the handle of a kitchen knife they believe to be the murder weapon, and that Kercher's DNA was found on the blade. They say Sollecito's DNA was found on the clasp of Kercher's bra.
Those findings were disputed by the defense, and the appeals court granted an independent review. A similar request had been turned down in the first trial.
The experts say in the report filed to the Perugia court on Wednesday that the genetic profile attributed to Kercher is "unreliable" and cannot be attributed with certainty.
They said results may have been contaminated on both the blade and bra clasp.
Regarding the blade, the experts said: "We believe that the technical tests are not reliable."
The experts also said the original testing did not follow any of the recommendations of the international scientific community for dealing with "low-copy number" DNA testing, which requires fewer human cells than traditional genetic testing methods.
They also said that "international procedures for inspection and international protocols for gathering and sampling exhibits have not been followed."
"It cannot be ruled out that the result obtained ... may stem from contamination," said the report's conclusions, obtained by The Associated Press.
The experts reached similar conclusions regarding the bra clasp. The bra was recovered at the crime scene only several weeks after the Nov. 1, 2007 fatal stabbing of the 21-year-old Kercher.
However, the review concurred with the original testing in saying that the genetic profile on the knife's handle could be attributed to Knox. The knife was found at Sollecito's apartment.
The findings are likely to please the defense, which had long maintained DNA traces were inconclusive and that they might have been contaminated when they were collected and analyzed.
The two experts - Stefano Conti and Carla Vecchiotti from Rome's Sapienza University - are to present their review in court on July 25.
The experts had been mandated to either conduct a retest or, if not possible, assess the accuracy of the original testing. They found that DNA traces were too small for a retest and so moved on to reviewing the original analyses to assess whether they were reliable and up to standard.
They sought an extension of about 40 days.
"It was a very complex job," Conti told the ANSA news agency in Perugia, minutes after submitting the report. "A huge amount of data has been examined and we have reached clear conclusions."