An Italian magistrate is due to decide later whether there is enough evidence to continue holding three suspects over the murder of Briton Meredith Kercher.
Meredith Kercher shared a flat with Amanda Knox
The suspects are American student Amanda Knox, 20, her Italian boyfriend Raffaele Sollecito, 24, and Congolese immigrant Lumumba Patrick Diya, 37.
The investigating magistrate must decide whether to make formal arrests.
Miss Kercher, 21, from Coulsdon, south London, was found with her throat cut at the flat she was renting in Perugia.
Police say Miss Knox crumbled under interrogation and now admits having been in the next room when Leeds University student Miss Kercher was murdered last week, but covering her ears to her flatmate's screams.
Mr Sollecito admits having lied to police by saying he was at a party on the night of Miss Kercher's death.
Police are examining two knives found in his possession.
On Thursday, through their lawyers, each suspect denied having been involved in Miss Kercher's death.
Mr Diya's lawyer said he had been at work at the time of Miss Kercher's death, while Mr Sollecito's lawyer said he had been at home.
Miss Knox's lawyer said she had had nothing to do with Miss Kercher's death and should be freed.
Miss Kercher's body was found in her bedroom on Friday morning in a pool of blood.
Police believe Miss Kercher was trying to fight off a sexual attack when she was killed.
The case presented by investigators said the suspects had all changed their story. They said Miss Knox had an unscrupulous tendency to lie repeatedly.
Police do not believe the murder was premeditated but they allege each of the suspects played a role.
Crucial to the case will be the suspects' phone records and calls they exchanged after the murder.
Police say they have good forensic evidence, including a footprint in the blood.
Police chief Arturo De Felice said Miss Knox claimed she was in the kitchen of the apartment she shared with Miss Kercher when Mr Lumumba went into the Briton's bedroom alone.
Miss Knox is reported to have told police: "I can't remember how long they were in there, but at one point I heard Meredith scream.
"I was horrified. After that I don't remember anything. I was very confused."
Mr De Felice said all three suspects were present at the murder scene.
Mr Lumumba had been in the country since 1988, while Mr Sollecito was a student at the local university. Miss Knox is from Seattle, Washington.