The man accused of murdering Tia Sharp told a prison officer that her death was an accident and said: "I'm not like Ian Huntley", a court has heard.
Stuart Hazell, who was taken to Belmarsh prison in August last year, was also quoted as saying that "nothing sexual" had happened between him and Tia.
Hazell is on trial on charges of sexually assaulting and murdering the 12-year-old between August 2 and 10 last year. He denies the charges.
Prison officer Warren Fegan, who was working at Belmarsh when Hazell was taken there, told the Old Bailey: "He was saying, 'I'm not like Ian Huntley, it was nothing sexual, I'm not a nonce'.
"He was saying that the press was trying to make it look like it was sexual but it wasn't," Mr Fegan testified.
"He said that it was an accident, she had fallen down stairs and broken her neck."
Hazell is the former boyfriend of Tia's grandmother Christine Sharp.
The schoolgirl's body was found in the loft of Ms Sharp's house in New Addington, south London, a week after she went missing.
A memorial to Tia in August last year Prosecutors say Hazell killed Tia and hid her body in the loft of the house.
Mr Fegan said: "He said that he didn't know what to do and he picked her up and took her upstairs and laid her on the bed, and he thought that she would get better.
"He didn't know what to do, so he wrapped her in a sheet and put her in the loft."
He said Hazell was full of remorse and felt sorry and guilty.
"He asked me how hard it would be to prove not guilty to murder but guilty to manslaughter," the prison officer told the court.
Mr Fegan told the jury that when Hazell was assessed at the prison, the risk of him harming himself was "at the far extreme".
"He really wanted to kill himself. He was saying he was sorry and he felt guilty.
"Initially he was fearing for his personal safety. He was very, very distressed. He was clearly saying that any opportunity he had he would kill himself."
Mr Fegan added: "He wanted to be dead. He wanted away from everything."
The prison officer said Hazell talked to him again two days later.
"He stated that he wished he could turn back the clock," Mr Fegan said.
He quoted Hazell as saying: "I deserve everything I get. If I get 25-30 years, I don't care, I deserve everything I get."
Mr Fegan said that, when he asked Hazell how he felt, he held up one hand, and said: "Guilty, guv'nor".
Prosecutor said the girl was sexually abused Another prison officer testified earlier today that Hazell had tried to get razors blades from his bag to cut his wrists while he was in custody at a police station.
Paul Leahy told the jury that Hazell said: "Since Friday I've been feeling guilty and I just want to kill myself."
The court heard that Hazell told Mr Leahy: "I have a real problem with my anger and when people say wrong things to me, I can flip.
"I just feel like hurting everyone."
According to Mr Leahy, Hazell said police should investigate his neighbours and insisted he had been "fitted up".
Hazell told the guard that the group of houses where he lived had interlinking lofts, and said someone had moved Tia's body into the space above the house he shared with the girl's grandmother.
He pointed the finger at Somali neighbours, using prison slang to describe them as sex offenders, and also said the girl had been the target of paedophiles, the court heard.
Tia's mother was in the courtroom as the prosecution continued to make its case against Hazell.
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