But in another controversial ruling, Judge Rodney Melville blocked a prosecution bid to show jurors photographs of the superstar’s “blemished” penis taken by police during another child sex investigation more than a decade ago.

The rulings came as prosecutors called a string of witnesses to counter testimony presented by the defence and in preparation for closing arguments, expected to be delivered next week.

Judge Melville dealt the performer a late blow by allowing the 12 jurors to view the potentially powerful video.

The move prompted Jackson’s lawyers to threaten to recall the accuser, his mother and two others to the stand.

Attorney Robert Sanger asked the four witnesses “be made available” to testify when the defence gets its turn at rebuttal.

The 15-year-old alleged victim has testified Jackson fondled him at his Neverland ranch in February or March 2003.

But the star claims the boy and his family made up claims against him after meeting lawyer Larry Feldman.

Mr Feldman represented another teenager who won a US$23m (A$30m) settlement from Jackson after making sex abuse claims.

Jackson was never charged in the 1993 case, but jurors learned of the claims and other uncharged child molestation allegations against him, as prosecutors sought to demonstrate that he is a repeat sex offender.

Jackson’s team says the current accuser’s mother is a swindler with a history of coaching her children to lie under oath, and who invented the claims only after learning of the huge settlement in the 1993 case.

Putting Jackson’s teenage accuser on the stand would give him a chance to rehabilitate himself after the defence highlighted inconsistencies in his testimony, said former prosecutor Craig Smith.

“There’s a definite downside in calling the accuser back,” Mr Smith told journalists outside the California courtroom.

Jackson is accused of sexually molesting the boy two years ago, serving him alcohol to seduce him and conspiring to hold him captive to ensure his silence.

The 46-year-old father of three has pleaded innocent to 10 charges that could land him in jail for up to 20 years if convicted on all counts.

On Thursday, Judge Melville denied a request to show jurors pictures of Jackson’s allegedly discolored penis taken by police during the 1993 investigation into allegations against the star.

Prosecutors were trying to show how his then accuser, who later won a multi-million dollar settlement, accurately described a blemish that was unique to Jackson’s anatomy.

Senior Deputy District Attorney Ron Zonen unsuccessfully argued this would prove Jackson’s relationships with with boys were “not casual.”