SANTA MARIA, Calif. – In a blow to Michael Jackson’s defense, prosecutors in his child molestation trial can introduce evidence of “past sexual offenses” by the pop star involving five young boys, a judge ruled on Monday.

The decision by Santa Barbara Superior Court Judge Rodney Melville means that jurors will hear testimony about a 1993 case that Jackson settled out of court for about $23 million.

The court can also hear from the son of a former Neverland Valley Ranch employee who claims the 46-year-old performer sexually abused him.

Melville said prosecutors could call up to nine witnesses to testify about inappropriate behavior by Jackson toward young boys between the ages of 10 and 13, including “Home Alone” star Macaulay Culkin.

Only one of the boys was expected to testify at the trial and a spokeswoman for Culkin — who has emphatically denied being molested by Jackson — told Reuters she did not expect the 24-year-old actor to be involved.

Legal experts said the ruling marked a turning point in the trial and threatened to swamp the defense with accusations of sexual misconduct by Jackson.

“It’s a huge blow to Jackson and great news to prosecutors,” said Andrew Cohen, a legal analyst following the trial for CBS News. Defense lawyers would be forced to prove that all nine new witnesses were lying about sexual misconduct involving Jackson, he said.

Among the allegations are that the singer thrust his hand into the pants of one boy — the son of a former Neverland housekeeper — licked the head of a second and was seen “kissing and hugging” a third.

Some of the witnesses will testify to abuse, while others will describe “grooming” behavior, which experts say enables a child molester to gain the trust of a potential victim.

Jackson was not present for Melville’s ruling but arrived later for testimony. He declined to discuss the decision with reporters as he left the court.

Lead defense attorney Tom Mesereau argued strenuously against admitting the evidence. He told the judge that prosecutors were trying to salvage a losing case with a parade of dubious witnesses who were out for financial gain.

Jackson is accused in a 10-count grand jury indictment of plying a 13-year-old boy with alcohol and molesting him while he and his family were staying at the entertainer’s Neverland Valley Ranch in early 2003.

He is also accused of child abduction, extortion and false imprisonment. The entertainer, who has pleaded not guilty, faces more than two decades in prison if convicted.

Jackson was never charged over the past accusations, but prosecutors want to convince jurors that he has a pattern of behavior toward young boys.

Actor George Lopez said on the witness stand he had met family members of Jackson’s accuser when the boy was recovering from cancer, but broke off contact after the father falsely accused him of stealing $300.