Expert Blames Stress for Amanda Knox's Conflicting Stories

PERUGIA, Italy Sept. 25, 2009— -- An expert suggested to an Italian court today that Amanda Knox's different versions of where she was on the night her roommate was murdered could have been the result of a great deal of stress she experienced as a foreigner being grilled as a homicide suspect.

Professor Carlo Caltagirone told the court in Perugia, Italy, that stress can affect memory, a phenomenon that he said has been studied extensively in both regular and forensic medicine.

"All aspects of memory can be modified by stress," Caltagirone told the court. "And certain circumstances can produce false recollections in perfectly normal people who are completely in good faith."

Knox, 22, is accused along with her former Italian boyfriend Raffaele Sollecito, 25, of murdering her roommate Meredith Kercher, 21. The Seattle student gave police conflicting versions of events in the days after Nov. 2, 2007 when Kercher's body was found semi-naked in a pool of blood in the apartment the two girls shared on the outskirts of Perugia.

Knox initially said she had spent night with Sollecito at his house, but later told police in the course of an overnight interrogation on Nov. 6 that she had a confused recollection of being in the house on the night of the murder and hearing Kercher scream. Knox implicated a third person, Patrick Lumumba, a pub-owner she worked for, saying he was in the house too.

Lumumba was later cleared of charges, and Knox corrected her version of events, returning to her statement that she had spent that night at Sollecito's house. The Italian Court of Cassation ruled in 2008 that Knox's statements about being in the house and hearing Kercher scream were inadmissible at the trial because a lawyer was not present when they were made.

These oral statements continue to be an issue at the murder trial, along with two written versions of her statement that Knox gave to police on Nov. 6 and 7.

Caltagirone explained how in highly tense and stressful situations, a person has a tendency to try to please the person he or she is talking to, and tell them what they want to hear.

Knox had previously testified that police harangued her and pressured her when they questioned her at length in the middle of the night. Knox testified that police insisted she had seen Lumumba because they found a text message from him on her phone, and that is why she eventually said he was there

Caltagirone could not speak specifically about Knox's state of mind that night, but he did say that in other cases he has studied he found that "when people are threatened, and accused of not remembering things, they become confused and cannot distinguish what they remember. It is as if they cannot manage their thoughts," he said.

The professor also said that a very young person who had only been living in a foreign country for a short time and who finds herself in such a situation "is certainly in a very stressful situation."

On the request on Knox's lawyers Caltagirone visited her in jail last spring, and spent a few hours with her. He gave he a psychological evaluation and found her to be in "very good general and cognitivecondition, typical of a girl of her age, with a flexible mind."

When Caltagirone was asked during cross-examination by prosecutor Giuliano Mignini whether the cartwheels and stretches Knox did in the police station that night did not indicate a relaxed frame of mind, he responded that "the cartwheels were certainly incongruous" but he felt they actually "reflected great stress" and by trying to relax, he said, she trying to "defend herself from such a stressful situation."

Walter Patumi, a coroner on the Knox defense team, also testified today. He discussed the knife that investigators believe is the murder weapon, reiterating what other defense experts have already said - that the large kitchen knife is not compatible with Kercher's wounds, and that the trace of Kercher's DNA police said they found on the blade is too small to be reliable.

Both Knox and Sollecito were in court on Friday. Both insist they are innocent and neither of them has missed a hearing.

A third person, Ivory Coast native Rudy Guede, has already been convicted of the murder. Prosecutors insist Guede, Knox and Sollecito killed Kercher during a drug fueled sex game gone wrong.

Also in court was Knox's father, Curt Knox, who has been present at a dozen hearings since the trial began on Jan. 16.

"I think today's hearing went very well," Curt Knox told ABC News. "Caltagirone brought up the fact that Amanda was interrogated by police for 41 hours over four days, and that that can lead to potential confusion in a high-intensity interrogation," he said. "It tells us that they took advantage of a very young girl, in the course of continuous, continuous, continuous interrogation," Knox added.