December 2001: Andrea Constand begins work as director of operations for the Temple University women's basketball team. In that role, she meets renowned alumnus Bill Cosby, who becomes her mentor and friend.
January 2004: Constand visits Cosby's mansion in Cheltenham Township. There, prosecutors say, Cosby drugs Constand and sexually assaults her while she is unconscious. Constand later moves back to her native Canada.
January 2005: Constand reports the alleged incident to Cheltenham police. Detectives interview Constand and Cosby.
February 2005: Bruce L. Castor Jr., then Montgomery County district attorney, says there is insufficient evidence to file criminal charges against Cosby. For a decade, Castor stands by his decision.
March 2005: Constand sues Cosby in federal court in Philadelphia. Though they are not named publicly, as many as 13 other women are prepared to testify against the entertainer, according to Constand's lawyers.
November 2006: Cosby and Constand settle out of court.
October 2014: During a performance in Philadelphia, the comedian Hannibal Buress assails Cosby as a rapist. Video of his remarks, delivered during a standup routine, goes viral and shines a new spotlight on the decade-old sex-assault allegations.
November 2014: Cosby cancels public appearances. NBC scraps a Cosby show under development.
December 2014: Cosby steps down from Temple University's board of trustees.
Spring 2015: Dozens of women make public allegations of unwanted sexual contact by Cosby. Nearly all their claims are beyond the statute of limitations; some are decades old. Cosby's lawyers say he has never assaulted anyone.
July 6, 2015: A federal judge in Philadelphia unseals portions of Cosby's deposition from the 2005 civil case. In it, Cosby admitted obtaining sedatives to give to women before sex.
July 10, 2015: Montgomery County District Attorney Risa Vetri Ferman reopens the criminal probe into Constand's claim.
August 2015: Investigators travel to Toronto to reinterview Constand about the alleged assault.
October 2015: Cosby becomes a central figure in the race for Montgomery County district attorney between Kevin R. Steele, Ferman's first assistant, and Castor, who is seeking his old job. Steele runs TV ads claiming Castor failed to prosecute Cosby. Castor counters that Steele could act to arrest Cosby.
Oct. 26: Constand files a defamation lawsuit against Castor, claiming he undermined her credibility for political gain.
Nov. 4: Steele wins the election over Castor.
Wednesday: Steele announces a charge of felony indecent assault against Cosby, a crime that carries a maximum penalty of a decade in prison. Cosby, now 78 and walking with a cane, is released after posting 10 percent of $1 million bail. His lawyers vow "a vigorous defense against this unjustified charge" and predict that he will be exonerated. - Laura McCrystal
and Emily Babay