"He knows we weren't there," American student Knox said moments after her accuser, Rudy Hermann Guede, left the courthouse. "I'm shocked and anguished by these statements."
The testimony by Guede, a 24-year-old immigrant from the Ivory Coast, was closely watched in the packed courtroom in Perugia. He had been called as a witness for the prosecution in the appeals trial of Knox and Raffaele Sollecito, her Italian ex-boyfriend and co-defendant.
Knox and Sollecito were convicted in the Nov. 1, 2007 slaying of Meredith Kercher, whose body was found in a pool of blood in the apartment she and Knox shared in Perugia.
Prosecutors claimed in Knox's first trial that Guede, Knox and Sollecito killed Kercher in what had begun as a sexual game.
Taking the stand, Guede confirmed the contents of a letter he wrote to his lawyers last year, in which he accused Knox and Sollecito of killing Kercher. In the March 2010 letter, which was read out loud in court, Guede wrote that he had nothing to do with the "horrible murder of the splendid and wonderful Meredith Kercher by Knox and Sollecito."
"This is a thought I've always had in my mind," Guede told the court Monday.
"It's not up to me to decide who killed Meredith Kercher," he added. "I've always said who was there that damned night in that house."
Guede said he was telling "the truth I lived through that night."
Guede is serving a 16-year-prison sentence for the murder. He sought a fast-track procedure and has already exhausted all levels of appeal. He was escorted in court by police in handcuffs.
Knox and Sollecito were convicted of sexual assault and murder in separate proceeding. She was sentenced to 26 years in prison, he to 25.
"Raffaele Sollecito, Guede and I have only been in the same place in a court," Knox said as she denied Guede's accusation.
"I don't know what happened that night," Knox added, saying she wished she could have said so to Guede's face.
She was only allowed to speak after Guede was escorted out.
"Amanda wanted to be able to stand up and tell him to tell the truth," said Edda Mellas, Knox's mother. "It's unfortunate that he continues to lie."
Guede was called by the prosecution to counter testimony by a fellow inmate and convicted child killer who claimed Guede told him during recreation time in prison that Knox and Sollecito had nothing to do with the killing.
On the stand, Guede denied talking to Mario Alessi about the case. The letter that was read in court had been written by Guede to deny Alessi's claims.
Witness Giacomo Benedetti, a close friend of Guede's who has often visited him in prison, told the court Monday that the Ivorian had never mentioned speaking to Alessi about the case.
Like Knox and Sollecito, Guede has denied killing Kercher. Unlike them, he has admitted being at the crime scene the night of the murder.
Speaking at the opening of his own appeals trial, Guede claimed he had heard Kercher and Knox argue minutes before the Briton was slain.
He said he was at the house with Kercher when he fell ill and went to the bathroom with his iPod. He heard Knox and Kercher argue over money, then heard a "very loud scream" coming from Kercher's bedroom, and rushed to it. There, he said, he saw an unidentified man who tried to attack him. Backing down into the hallway, Guede said he heard the man say "Let's go, there's a black man in the house."
Guede said he heard footsteps leaving the house and looked out of the window, where he saw a silhouette that he later identified as Knox's. He said he then tried to rescue Kercher after her throat was slit, taking her in his arms and trying to mop up the blood with towels. But he panicked and left the house.
Guede fled Italy, and was found and arrested in Germany about a month after the killing. His DNA confirmed sexual intercourse with Kercher, while fingerprints and other traces attested to his presence in the house.
Knox and Sollecito have maintained they were at Sollecito's house the night of the murder. Their defense lawyers claim Guede was the killer and acted alone.
Sollecito, also addressing the court Monday, said his and Knox's lives had been ruined on the basis of "shadows" and "voices."
Two other witnesses were called to counter testimony by another defense witness, a Naples mobster named Luciano Aviello who had told the court earlier this month that his brother had killed Kercher during a botched burglary. Aviello's brother is on the lam.
The two witnesses - two inmates at the same prison as Aviello - testified that Aviello had said he had been contacted by Sollecito's defense team to stir up confusion in the trial in exchange for money. Witness Alexander Ilicet of Serbia-Montenegro said Aviello had wanted the money for a sex-change operation.
Sollecito's defense has denied making any such contact.
