[Update 4:15 p.m.: Former prosecutor Bruce Castor testified on Tuesday that his decision not to charge Bill Cosby with any sex crime in relation to the actor's relationship with Andrea Costand prohibits the county from brining an new charges in the case.]
A former district attorney who says he struck a "non-prosecution" deal with Bill Cosby in return for the actor's testimony in a civil lawsuit will be Mr. Cosby's star witness on Tuesday, as his lawyers attempt to throw out the only criminal case brought against him, despite years of allegations that he drugged and sexually assaulted dozens of women.
Bruce Castor Jr. promised Cosby he would not be prosecuted if he testified freely in a 2005 civil lawsuit brought by Andrea Constand, the former Temple University women's basketball team manager who claims that Cosby gave her pills and sexually assaulted her in 2004. Cosby calls the incident consensual. The civil case was settled for undisclosed terms in 2006.
His testimony, however, was released in 2015, and the actor has now been charged with felony sexual assault against Ms. Constand. Cosby, who has not yet entered a plea, will appear in court in Norristown, Pa., on Tuesday.
Although allegations of sexual assault have swirled around Cosby for years, intensifying recently as more women have come forward with their stories. Many are barred by expired statues of limitations.
Many of their stories involve drugs. In the 2005 disposition, Cosby admitted to giving Constand three half-pills of Benadryl at his home; he also said he had obtained quaaludes, a powerful sedative, to give to women before sex, but maintained that he had offered them to women with consent.
Depositions are pre-trial statements from witnesses under oath, and typically can be used in prosecution. Mr. Castor says that he reached an oral "no-prosecution" deal with Cosby and his lawyer, who died last year, in return for Cosby's testimony in the civil lawsuit.
Castor is expected to testify Tuesday on Cosby's behalf, as his lawyers argue that the felony charges should be dismissed.
Kevin Steele, the new Montgomery Country district attorney who brought charges against Cosby just before the statute of limitations expired, says that Castor's immunity deal would require written documentation. When asked for a written agreement last fall, Castor offered a 2005 press release about the case.
Making a civil case deal, and an unwritten one, "is an extremely unusual arrangement," Lynne Abraham, a Philadelphia judge and former district attorney who is not involved with the case, told the Associated Press.
This report includes material from Reuters and the Associated Press.