Knox 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 Meredith 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, saying, as she had initially, that she had spent the night when Meredith was killed at Sollecito's house. The Italian Court of Cassation ruled in 2008 that Knox's statements were inadmissible in trial since a lawyer was not present when they were made.
These statements continue, however, to be an issue at the murder trial, along with two written statements Knox gave police on Nov. 6 and 7 in which she confusedly confirms. The written statements have been admitted in this trial.
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, in testimony she gave in court last June, said that police harangued her and pressured her when they questioned her at length in the middle of the night. She said they 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 cognitive condition, 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.
Also in court was Knox's father, Curt Knox, who has been present at a dozen hearings since the trial began on Jan. 16.