By Christian Fraser
BBC News, Perugia
The first rule of any murder investigation is to eliminate the people closest to the victim.
Meredith Kercher was studying in Perugia as part of her degree
But in this case, the evidence points one way. Meredith Kercher knew her killers.
There are three suspects.
Her American flatmate Amanda Knox, who allegedly confessed to police she was in the kitchen at the time of the murder.
Ms Knox's Italian boyfriend, 24-year-old Raffaele Sollecito, who was a student at the University of Perugia, and the owner of a student bar in the city - 37-year-old Diya Lumumba, a Congolese immigrant known as Patrick.
They are all being questioned on suspicion of murder and sexual violence.
Pool of blood
Meredith Kercher's body was found in her bedroom on Friday morning.
Police had arrived at the house with Ms Kercher's two mobile phones which they had recovered from a neighbour's garden.
When they got there they found Amanda Knox and her boyfriend.
Ms Knox had called her friends to report a break-in. They had returned from a night out, said the 20-year-old student, to find the door ajar. There was blood in the bathroom and Ms Kercher's door had been locked.
Police broke down the door to find Ms Kercher's body partially clothed and lying in a pool of blood.
She had been stabbed in the throat, said the coroner, with a penknife or a sharp piece of glass. Police think she was trying to fight off a sexual attack.
The chief of police, Arturo De Felice, said so far the three suspects have all presented conflicting stories.
They were all present at the murder scene, he said - each playing a different role - but the murder was not pre-meditated.
In the Italian press, Ms Knox is reported to have told police that Mr Lumumba had gone into Ms Kercher's bedroom alone.
"I cannot remember how long they were together," she said.
"I can only say that at one point I heard Meredith scream. I was horrified. I put my fingers in my ears.
"After that I don't remember anything. I was very confused."
The chief of police confirmed the reports were accurate. The public prosecutor is said to have opened a separate inquiry into the leaking of the transcripts.
The police also say the mobile phone records of the three suspects are significant.
"If I told you I was in Rome, but the records showed I was in Paris then you might begin to ask questions," Mr De Felice said.
When presented with this evidence, he added, Amanda Knox had "crumbled".
The three suspects met at Le Chic, a bar owned and run by Mr Lumumba. Ms Knox had also worked for him, handing out promotional flyers.
Amanda Knox and Raffaele Sollecito were dating
She had only been in Perugia since August, but through her work had met Italian Raffaele Sollecito.
His website shows him holding a meat cleaver.
"I am very honest," he says. "Peaceable, sweet, but sometimes I am totally crazy."
The three suspects are being held in isolation without access to their lawyers.
Police spent Wednesday considering the testimony they have given. They are not expected to be interviewed again until charges have been brought.
On Thursday, prosecutors will go before a judge to present their case and secure a formal arrest.
Meanwhile, Ms Kercher's family have visited the cathedral in Perugia where, on Monday, her friends and fellow students laid candles and a poster in her memory.
Her father left his own candle and this brief message: "I love you forever Meredith. All my love, Dad."