Italy- The American student and her Italian boyfriend suspected of involvement in the murder of Meredith Kercher in Perugia bought “sexy underwear” and talked about having “wild sex” the day after her body was discovered, according to an Italian shopkeeper.

Today Italian papers carried leaked testimony given to police by Carlo Maria Scotto di Rinaldi, 30, the owner of a clothing shop in Perugia.

He said he clearly remembered Amanda Knox and Raffaele Sollecito coming into his shop at about 7pm on Saturday, November 3, two days after Ms Kercher was killed and a day after the couple had first been questioned. Their visit had been recorded on the shop’s CCTV cameras, he said.

He said they stayed about half an hour, and Ms Knox had bought two thongs. “They were all over each other all the time, kissing and embracing,” Mr Scotto di Rinaldi told police. “Their behaviour was so exhibitionist all the other customers were looking at them”. He said as the couple were paying at the till he overheard Mr Sollecito say to Ms Knox “You can put these on at home and we’ll have wild sex.”

The murder of the 21-year-old student from London has appalled publics in Britain, Italy and the US.

They had talked in English,”but I know the language and had no difficulty in understanding”, Mr Scotto di Rinald said. La Stampa commented that the couple’s behaviour was “not exactly normal”, adding: “But then, what is normal about this story?”

Yesterday Italian police said that DNA taken from the toothbrush of Rudy Hermann Guede, the “fourth suspect” in the case, indicated that he had had “violent and incomplete sex” with Ms Kercher on the night she died. Tests had confirmed that the bloody fingerprint on her pillow corresponded exactly to Mr Guede’s, while his DNA matched samples taken from Ms Kercher’s body and on toilet paper.

Mr Guede – who is in German police custody awaiting extradition to Italy – had denied being at the cottage that Ms Kercher and Ms Knox shared on the night of the murder. He has now admitted that he was there and had sex with Ms Kercher, but has insisted he did not kill her and maintains he is innocent.

Mr Guede did not mention Ms Knox in his account to German police, but in at least one of the several versions she has given to Italian police the American student has admitted also being at the cottage during the murder. She said that she heard screams from Ms Kercher’s bedroom, but named the assailant as Diya “Patrick” Lumumba, a Congolese bar owner for whom she worked, rather than Mr Guede. Mr Lumumba has now been released for lack of evidence.

Police said phone records showed that Mr Guede and Ms Knox had talked on their mobile phones “several times” both before and after Ms Kercher’s death.

Mr Guede claimed that Ms Kercher had been murdered by “an Italian guy with brown hair who I don’t know” – an apparent reference to Mr Sollecito, who maintains that he was at his flat all evening and all night.

Mr Guede says that he was invited by Ms Kercher to the cottage, where they had sex. He said he then went to the bathroom because of “stomach pains”, heard the doorbell ring, and shortly afterwards heard the British woman scream from her bedroom. He said he that emerged from the bathroom to confront the “brown-haired Italian”, that they fought, and that he then fled, injured, from the scene after trying in vain to resuscitate Ms Kercher, who was “covered in blood”.

Italian police suspect that it was Mr Guede who killed Ms Kercher. Claudia Matteini, the investigating judge, said: “There are, without doubt, grave indications of the guilt of Guede, especially in the light of precise and irrefutable analysis carried out by the forensic police.”

Ms Knox saidin a rambling handwritten note for police on the night after her arrest, and leaked this week to Italian newspapers, that her initial confession to involvement in the killing was made “under the pressures of stress, shock and extreme exhaustion”. She said that she was warned she would be arrested and put in jail for 30 years, and that police struck her on the head when she could not remember what happened. Police in Perugia deny that Ms Knox was mistreated during questioning.

In her statement Ms Knox – who has admitted smoking cannabis with Mr Sollecito on the day of the crime – said that she had accused Mr Lumumba because his “blurred image” had “flashed across my mind”, but she could not be sure whether it had been a dream. She said she was not sure what was a dream and what was reality, and added: “All I know is that I didn’t kill Meredith.”