Italian prosecutors believe that Rudy Hermann Guede, a suspect in the murder of Meredith Kercher in Perugia, had a rendezvous not with Ms Kercher on the night of the killing, as he claims, but with Amanda Knox, her American flatmate, because she owed him money for drugs.

Mr Guede, the Ivory Coast immigrant who was extradited from Germany last week, is due to appear today before a judge reviewing his detention. Sources close to the investigation said that in explaining why Mr Guede should not be freed Giuliano Mignini, the chief prosecutor, would offer a reconstruction of the crime revolving around drug dealing.

Police believe that Mr Guede, who is being held in the same prison as Ms Knox and Raffaele Sollecito, her Italian boyfriend, supplied hashish to them both. Both have admitted "being high" on cannabis on the day of the murder, though both maintain that they were at Mr Sollecito's flat the whole evening and night and not at the cottage where the killing took place.

Mr Guede, who has a record of minor drugs offences in Italy, has told police that he met Ms Kercher by arrangement, and that she complained to him that Ms Knox had stolen money from her bedside drawer to pay for drugs. Prosecutors suggest this is a distorted version of what actually happened: that Mr Guede and Ms Knox met at the cottage, that Ms Knox took Ms Kercher's money to pay him, and that Ms Kercher walked in at "the wrong moment". In the ensuing confrontation Ms Kercher was sexually attacked and her throat was cut.

New witness 'saw Meredith suspects together'

Amanda Knox, Raffaele Sollecito and Rudy Guede were see at the house in Perugia where the American student died

Multimedia

• Murder in Perugia

BACKGROUND

• Meredith Kercher: Q&A

• New DNA not from Meredith suspects

• Timings crucial to Kercher murder investigation

Related Links

• Meredith called Knox 'drugged-up tart’

• Meredith suspect 'can identify real killers'

• Meredith suspect flown back to Italy

In a memorandum written while he was in custody in Germany and leaked to Italian papers Mr Guede said that Ms Kercher had complained to him at their rendezvous at the cottage that Ms Knox was a "drugged up tart". Police believe she may indeed have used such words, but in the presence of Ms Knox herself as well as Mr Guede. Il Messaggero, the Rome daily, said that the alleged role of Mr Sollecito in the murder as reconstructed by the prosecutors remained unclear, though police believe that the murder weapon was a kitchen knife from his flat.

A woman who lives opposite the cottage has told police that she heard screams coming from it at about 11pm, after which "at least two people" emerged and fled "in different directions". She said she had gone to sleep about 9pm or 9.30pm, and had been woken up by the scream and the running. "I didn't look at the time, but I think it was a couple of hours after I went to sleep".

Police said that this contradicted Mr Guede's account, in which he claimed he had stayed behind to try and help Ms Kercher after the assailant had fled. He said that he been in the bathroom with stomach pains when the murderer entered the cottage which Ms Kercher and Ms Knox shared. He had heard "terrible screams" and on emerging had seen " a figure with his back to me in her bedroom. He turned round. It was an Italian man, I know this because he insulted me and did not have a foreign accent."

He said that the man had a knife in his hand "and tried to strike me with it. I tried to defend myself with my hand." The assailant had rushed out of the house, saying "a black man found is a guilty man". Italian reports said that Mr Mignini would argue that this account was "improbable and contradictory" and designed to cover up Mr Guede's own alleged "criminal actions".

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