The American housemate accused of murdering Meredith Kercher in Perugia told police that she heard the British student scream from another room but put her fingers in her ears.

Detailed excerpts of Amanda Knox’s witness statement were released by Italian police this morning and detectives have claimed that her confused account of the evening implicates her in the death of her friend.

Police said that Ms Knox, 20, who slept in the bedroom next to Ms Kercher, confessed to a criminal act. Her boyfriend, Raffaele Sollecito, 23, from Bari, southern Italy, and Patrick Diya Lumumba, 37, of Perugia, are also being held.

Ms Kercher was found partially clothed in her bed on Friday morning with her throat cut. Detectives believe that the Leeds University exchange student, who was studying in Perugia, was killed between midnight and 2am after refusing to take part in a violent orgy on Thursday night.

Police have said that they now consider it an open and closed case, but no one has yet been charged.

Ms Knox told police that it was Mr Lumumba, a Congolese immigrant who runs a bar called Le Chic, who was in Ms Kercher's bedroom and that she herself only "heard the screams". She said that she heard "thuds" and could "imagine what was happening".

Her boyfriend, who the police believe was also involved in the murder, cast doubt on her testimony in his own statement to police. He said he saw Ms Knox leaving on the morning after the murder with an empty plastic bag and returning later wearing different clothes.

"In my former statement I told you a load of rubbish because I believed Amanda's version of what happened and did not think about the inconsistencies," he said.

The police however said both Ms Knox and her boyfriend had given confused and partial accounts, which they say were "full of holes" and apparently designed to show that their role was "marginal".

Mr Sollecito claimed that he was not at the house that evening, but police said that the footprint found in a pool of blood in Ms Kercher's bedroom was "compatible" with his, and that a penknife found in his possession could have been the murder weapon.

According to the Italian media, a pathologist's report suggests that at least two people were involved in the murder, with one holding Ms Kercher down while the other "sexually violated" her. When asked if she had held Ms Kercher down Ms Knox "burst into tears and went into a state of shock", Italian reports said.

Edda Mellas, Ms Knox’s mother, set off for Perugia from her home in Seattle to comfort her daughter after hearing that she had discovered the body of her flatmate, and learned en route that she was being treated as a suspect.

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