Amanda Knox Trial: DNA Expert Takes Stand in Support of Knox

Sept. 28, 2009 — -- After months of hearings and more than 100 witnesses, the final witnesses took the stand in the Amanda Knox trial over the weekend in Perugia, Italy.

Knox, an exchange student from Seattle, is accused, along with her former Italian boyfriend Raffaele Sollecito, 25, of sexually assaulting and killing British student Meredith Kercher, 21, with whom Knox shared a cottage on the outskirts of the picturesque Italian hill town.

Among the final witnesses was Sarah Gino, a DNA expert called by Knox's defense team, who took aim at the kitchen knife prosecutors believe was used to murder Kercher.

Prosecutors say Knox's DNA was found on the knife's handle, and that her roommate Kercher's DNA was found on the blade.

But Gino told the court that the DNA taken from the knife was too miniscule to be reliable and that the knife easily could have been inadvertently contaminated.

Gino also said the prosecution provided amplified DNA samples that were missing dates. She called the DNA amplification -- the process of copying a small DNA sample to examine it -- the "key moment" in DNA analysis.

The dates are important, Gino said, "because they would tell us what samples were tested together on the same day, which might indicate if some of them could have been contaminated."

She said dating the procedure for each sample was important to ensure that the amplification did not happen twice by mistake.

"DNA does not have wings, but it flies," she said about the possibility of contamination in the police lab. "In a laboratory, where hundreds of samples are examined, the risk of contamination exists and should be taken into consideration."

Prosecutors Accuse Amanda Knox of Fatally Stabbing Kercher

Prosecutors have tried to convince the court that Sollecito held Kercher by the shoulders while Knox fatally stabbed her.

The defense team points out that it's never been proven that this was the actual knife used to murder Kercher.

Gino was one of the last two witnesses to testify during what has become known in Italy as the "trial of the century."

With closing arguments expected next, Knox's defense team will point to the questions surrounding the knife and the fact that none of Knox's DNA was found in Kercher's bedroom.

They will likely point to Knox's testimony in which she explained discrepancies in her stories to police, saying that her confused statements were a result of brutal police interrogation, during which investigators slapped her on the head and called her a "liar" as she was questioned.

Finally, the defense will point to a third person, Rudy Guede, a local drug dealer who was convicted in October 2008 of playing a role in Kercher's killing and sentenced to 30 years in prison.

Kercher was found dead in her bedroom Nov. 2, 2007, semi-naked with her throat cut.

Guede has admitted he was at the house the night of the murder but says he did not kill Kercher. Knox's defense team has argued that it was Guede's DNA -- and his alone -- that was found in the room where Kercher was murdered. The prosecution says Sollecito's DNA was found in the room on Kercher's bra, but defense claims that evidence was the result of contamination.

there has been no evidence presented -- DNA or otherwise -- suggesting Knox's presence in the room.

At the next hearing in the trial, scheduled for Oct. 9, lawyers for Knox and Sollecito are expected to request the appointment of an independent expert to evaluate conflicting DNA and physical evidence.