'I wanted it to stop': victim describes alleged Cosby sex assault
Actor Bill Cosby speaks at the National Action Network's 20th annual Keepers of the Dream Awards gala in New York April 6, 2011. REUTERS/Lucas Jackson

Bill Cosby's primary accuser testified on Tuesday that she felt "frozen" after taking three pills the once-beloved entertainer gave her and that he sexually assaulted her.

Andrea Constand's voice quivered in her first day of testimony as she described the 2004 incident at Cosby's Philadelphia-area home while Cosby, 79, at times shook his head.

"In my head, I was trying to get my hands to move, my legs to move, but I was frozen," she said after describing how Cosby had spent months gaining her trust.

"I wanted it to stop," she said, referring to the sexual assault.

Dozens of women have accused Cosby of sexual assaulting them, often after plying them with drugs, in a series of attacks dating back to the 1960s. Every accusation but Constand's is too old to be the subject of criminal prosecution, and the outcome of trial in Norristown, Pennsylvania hinges on whether jurors are persuaded by her testimony.

(Editing by Scott Malone and Bill Trott)