The credibility of the boy who accused Michael Jackson of sexually abusing him is in doubt after a claim he recently signed legal papers saying the singer "never acted inappropriately".
It also emerged that the boy's family had made two other abuse-related lawsuits in the past, winning a €130,000 settlement in one case.
The new developments came amid signs that the health of the 12-year-old cancer survivor at the centre of the allegations had deteriorated.
San Francisco Assistant District Attorney Kimberly Guilfoyle Newsom said she had heard a tape in which the boy, his mother and brother say Jackson "never acted inappropriately".
She said the 20-minute tape was played to her by a private investigator working for Jackson, shortly after the Martin Bashir documentary was broadcast earlier this year. The programme caused a storm as Jackson admitted letting boys sleep in his bedroom.
Ms Newsom told CNN that the accuser and his mother had also signed an affidavit earlier this year, stating that Jackson never abused him.
The development could undermine the case against the 45-year-old star unless prosecution lawyers can prove that abuse happened after the tape and affidavit were produced.
Jackson has described the allegations against him as a "big lie". But the District Attorney of Santa Barbara, in California, Mr Tom Sneddon, who announced the arrest warrant for Jackson last week, defended the prosecution.
"We didn't go looking for this case. It came to us," he told CNN. "I would not have filed the charges had we not had a victim we felt was co-operative and supportive."
The scandal appears to be hitting Jackson's record sales in the US. His new album, Number Ones, was forecast to enter the US chart at number 13 at the weekend.
PA