A new suspect has emerged in the murder case of Meredith Kercher, the British student murdered in a frenzied attack in Perugia last November.

Witnesses have said that a man was seen near the scene of the crime covered in blood and screaming: “I killed her, I killed her.”

He is described as blond with blue eyes, aged about 30, and wearing a fleece decorated with the Norwegian flag and a white woollen hat. Paramedics who found him wandering around, dazed, say that his hands, clothes and shoes were all bloody.

The emergence of another suspect raises further questions about the police investigation.

Ms Kercher, 21, had just begun an Erasmus studies course in Perugia when she was murdered at the whitewashed hillside cottage that she shared with Amanda Knox, an American student, and two female Italian students. Prosecutors allege that she was forced to her knees and had her throat cut after she refused to take part in a drug-fuelled sex game.

Three suspects in the case — Ms Knox, 20, her former Italian boyfriend Raffaele Sollecito, 24, and Rudy Guede, 20, an Ivory Coast immigrant and basketball player — are being held in prison. Appeals for their release have been rejected and investigators say that they will present their findings to a judge next month.

A fourth suspect, Diya “Patrick” Lumumba, a barman and musician of Congolese origin accused by Ms Knox of being the murderer, has been released because of a lack of evidence, but remains under investigation.

The existence of a fifth suspect apparently came to light by chance when local reporters in Umbria were writing an article about the local ambulance service. One of the doctors being interviewed said: “What happened to that boy with his shoes covered in blood in the Meredith Kercher case? We never heard any more about it.”

Asked to explain, the doctor told the reporters: “He was someone we knew well. We had often picked him up and had to deal with him.”

Members of the ambulance crew who found the man said that they had spotted him at 7am on November 2, several hours before Ms Kercher’s body was found at Piazza Grimana, a small tree-lined square and basketball court between the cottage and the University for Foreigners.

The man was washing his bloodied hands under a fountain. The paramedics said that when they approached him he had shouted: “Get out of here, all hell is going to break loose soon.” Other people in the square told the ambulancemen that they had seen the man in a phone box screaming down the phone: “I’ll kill you, you whore.”

“The hypothesis must be that a killer is still at large,” the newspaper La Stampa said. However, sources close to the murder investigation said that the man in question was a well-known drug addict in Perugia and had already been “taken into account”. Police had established that the woman he screamed at on the phone was his girlfriend. The man had been taken to hospital after being found by the paramedics, and then transferred to a home for drug addicts where he remained under close observation, investigators said.

Luca Mauri, a lawyer for Mr Sollecito, said that he would ask for the evidence about the “fifth suspect” to be put on the record. His description tallied with that given of the murderer by Mr Guede, who admits being at the cottage on the evening of the murder, but maintains that he was in the lavatory when the killer entered.

Defence lawyers said that Mr Guede had told investigators that the intruder resembled Mr Sollecito, but his description could equally well apply to the “fifth suspect”.

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