NORRISTOWN, Pennsylvania (AP) — The chief accuser at Bill Cosby’s sexual assault retrial talked about framing a celebrity before going to police with her allegations in 2005, a key defence witness testified yesterday as the TV star’s lawyers began putting on their case.

Marguerite Jackson, an academic adviser at Temple University, said Andrea Constand told her she could fabricate sexual assault allegations and “get that money” from a civil suit, bolstering Cosby’s efforts to show Constand made up the allegations against him to extort a big civil settlement.

Jackson’s account was immediately challenged by prosecutors, who suggested she wasn’t on the trip where she says her conversation with Constand took place.

Her appearance on the witness stand was one of the most highly anticipated moments of a retrial that has Cosby, 80, defending himself against criminal charges that he knocked Constand out with pills and then sexually assaulted her at his suburban Philadelphia home in 2004. Cosby’s lawyers call Constand a “con artist” who set him up. The famed comedian paid her nearly US$3.4 million in 2006.

Jackson recounted a conversation she said she had with Constand on a road trip to the University of Rhode Island with the Temple University women’s basketball team, where Constand was working as operations director.

After watching a TV news report about a celebrity who had been sued over allegations of sexual assault, Jackson said Constand told her: “Oh wow, something similar happened to me.” Constand said she never reported the assault because her assailant was a “high-profile person” and she knew she couldn’t prove it, Jackson testified.

Jackson, who said she roomed with Constand on the trip, told jurors she encouraged Constand to come forward. She testified Constand then switched gears, saying: “No it didn’t, but I could say it did. I could say it happened, get that money. I could quit my job. I could go back to school. I could open up a business.”

Jackson said the conversation happened February 1, 2004, a few weeks after Constand says Cosby molested her.

Constand denied rooming with Jackson and testified Monday she didn’t “recall ever having a conversation with” her.

During Jackson’s cross-examination, a prosecutor produced Temple records showing Jackson’s travel to other away games but not to the one at the University of Rhode Island. The defence did not produce any records to support Jackson’s claim she was on the trip.

Jackson testified she was aware of the 2005 criminal probe, Constand’s subsequent lawsuit and her big financial settlement with Cosby, but never told anyone in Cosby’s camp — even though Cosby was represented at the time by Patrick O’Connor, the chairman of the board at Temple, where Jackson got her degree and has worked for 31 years.

She said a comedian she met on a cruise put her in touch with Cosby’s lawyers in November 2016. They got to talking about Cosby after the comedian offered to buy her a drink and promised, “I won’t put anything in it,” she recalled.

“They came in. Took my statement. The whole nine,” Jackson said. “They called me to testify, then they didn’t allow my testimony.”

Judge Steven O’Neill blocked Jackson from taking the stand at Cosby’s first trial last year, ruling her testimony would be hearsay after Constand told the jury she didn’t know her. That trial ended without a verdict after jurors deadlocked.

The judge changed his mind about Jackson for the retrial, giving the defence case a huge boost.

Outside court, Cosby spokeswoman Ebonee Benson said investigators intentionally ignored Jackson’s allegations because they’ve “always known how damaging this testimony would be”.

The defence case was scheduled to resume today.