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Matt Rourke, Pool, Associated Press
Bill Cosby, center, accompanied by lawyers Fortunato N. Perri, Jr., top left, and Brian McMonagle, left, walks from the Montgomery County Courthouse during his sexual assault trial, Tuesday, June 6, 2017, in Norristown, Pa.

NORRISTOWN, Pa. — Bill Cosby's chief accuser says she shot down the actor's casual advances twice before she found herself paralyzed and unable to fight him off the night she took pills he said were herbal supplements.

Andrea Constand emerged from 12 years of silence Tuesday to testify at Cosby's sexual assault trial. She will return to the witness stand Wednesday.

Constand has told jurors how her professional relationship with the Temple University trustee evolved into a friendship.

She says Cosby became more flirtatious and suggestive over time, once grabbing her thigh and later attempting to unbutton her pants. She says she made it clear she didn't welcome the behavior.

The 79-year-old Cosby could spend the rest of his life in prison if convicted.

The defense says the relationship with Constand was consensual.