Bill Cosby faces sexual assault charge

US actor Bill Cosby has been charged with sexually assaulting a woman at his home 12 years ago - the first criminal charges brought against the comedian out of the torrent of allegations that destroyed his good-guy image.

He has been charged with aggravated indecent assault in a case that sets the stage for one of the biggest Hollywood celebrity trials, and which could see the 78-year-old jailed in the twilight of his life.

In bringing the case, Montgomery County District Attorney Risa Vetri Ferman overruled her predecessor, who declined to charge Cosby in 2005 when a Temple University employee first alleged that the comic drugged her and violated her at his mansion in suburban Philadelphia.

The TV star acknowledged under oath a decade ago that he had sexual contact with the woman but he said it was consensual.

The charges were announced just days before the 12-year statute of limitations for bringing charges was set to run out.

Pennsylvania prosecutors reopened the case over the summer as damaging testimony was unsealed in a related civil lawsuit against Cosby and as dozens of other women came forward with similar accusations.

Many of those alleged assaults date back decades,...