NORRISTOWN, Pa. - Disgraced US megastar Bill Cosby paid $3.38 million to a former university employee who accuses him of sexual assault, his retrial heard Tuesday in a dramatic revelation in a lengthy prosecution opening statement.

The now 80-year-old Cosby could spend the rest of his life behind bars if convicted of drugging and molesting Andrea Constand at his Philadelphia home in 2004.

The pioneering black entertainer's first trial ended in a hung jury in June last year, with a sequestered panel hopelessly deadlocked after six days of testimony and 52 hours of deliberations.

The case forever tarnished the legacy of an actor once adored by millions as "America's Dad" for his defining role as lovable father and obstetrician Cliff Huxtable on hit 1984-92 television series "The Cosby Show."

On Tuesday, Montgomery District Attorney Kevin Steele revealed in public that the actor paid 44-year-old Constand $3.38 million as part of a previously undisclosed civil settlement to her claims in 2006.

In long, at times rambling remarks kicking off perhaps the most high-profile case of his career, Steele rehashed much of the "he-said, "she-said" case, quoting liberally from Cosby's prior deposition.

Steele sought to neuter a potential attempt from the defense to portray Constand as a scheming money-grabber by saying his office had approached her - not the other way - once new evidence came to light.

"We're very confident that you will convict the defendant on three counts of aggravated, indecent assault for what he did to Andrea Constand on that night in January 2004," Steele told jurors.

"She was incapable of consenting to anything," he added.

In recent years, some 60 women have accused the Emmy-winning Cosby, who today claims to be legally blind, of being a serial predator, alleging that he drugged and assaulted them over a span of 40 years.

Yet the three counts of aggravated indecent assault in connection with Constand, who now lives in Canada, are the only criminal charges to stick against Cosby.

His retrial is the most high-profile criminal case since the start of the #MeToo era, the US cultural watershed that has ruined the careers of a string of powerful men in Hollywood, politics and the media. - AFP