Mr Sollecito maintains he was in his own home all night
A man accused of killing UK student Meredith Kercher did not use his computer on the night of her murder - as he had claimed - a court has heard.
Italian Raffaele Sollecito, 24, has maintained he was at his own apartment that evening, working on his computer.
Police officer Marco Trotta told the jury that tests showed no one worked on the computer during the night Ms Kercher was stabbed to death, in 2007.
Mr Sollecito and his ex-girlfriend Amanda Knox, 21, deny the murder.
Last year a third person, Rudy Guede, was convicted of the killing and sentenced to 30 years in jail. He had admitted to being in the house at the time of the murder but denied any wrongdoing.
Prosecutors say Ms Kercher was killed during a violent sex attack by Ms Knox, Mr Sollecito and Guede.
Prosecutors maintain there is DNA evidence on a knife and on Ms Kercher's bra allegedly linking Mr Sollecito to her death.
Ms Kercher, a Leeds University student from Coulsdon in south London, had been studying and living in the Umbrian university town of Perugia when she was killed on 1 November 2007.
She shared a house with Ms Knox, who was on a student exchange from the University of Washington.
On Saturday Mr Trotta showed the court videos detailing technical simulations his team carried out on Mr Sollecito's computer, saying there was "no human interaction" between 2110 GMT on 1 November and 0532 GMT on 2 November.
A second computer belonging to Mr Sollecito also showed no activity but the suspect had himself admitted it had been broken before the crime was committed.
Ms Kercher's body was discovered half-naked in the bedroom of her shared house, on 2 November. Her throat had been cut.
She is believed to have died between 2100 and 2300 on 1 November, according to court documents.
Luca Maori, one of Sollecito's lawyers, said the defence would challenge the computer findings.
The court was also told by Ms Knox's Italian professor, Antonella Negri, that the American student wrote an essay in the form of a letter a few days after Ms Kercher's death.
"She wrote a letter to her mother, describing her mood. She was worried and confused and she wanted her mother to travel to Perugia so she could distract herself and they could go shopping together," she told the court.
The professor described Ms Knox as "a good student, intelligent and willing".
On Friday the trial heard Mr Sollecito had told police during questioning that he was "a fan of arms and knives".
Police officer Daniele Moscatelli said the accused looked "quite confused and nervous" during his questioning by police in the hours after the murder.
Another police officer, Fabio D'Astolto, told the court that in the same period Ms Knox "was nervously walking up and down the hallway, bringing both hands to her head and hitting it".