PHILADELPHIA -- An ex-prosecutor is expected to testify that he promised Bill Cosby would never be charged over a 2005 sex-assault complaint, but a judge must decide if that constitutes an immunity deal.
Then-prosecutor Bruce Castor will be a key witness for the defense at a Feb. 2 hearing over what Cosby's lawyers have called a "non-prosecution agreement."
The defense argues that prosecutors who charged Cosby last month unfairly used his deposition testimony from the accuser's civil lawsuit against him. Castor supports their position.
But Montgomery County District Attorney Kevin Steele, the prosecutor handling Cosby's case, said there is no evidence of a signed immunity agreement. Cosby's lawyers did not attach one to their recent motion to dismiss the case.
On Saturday, Andrea Constand's lawyer said she never knew of such an agreement.
"He (Castor) said ... that he talked to us about it. That's a lie," lawyer Dolores Troiani said. "It never happened."
Castor, in announcing that he wouldn't charge Cosby in 2005, had warned both sides that he could revisit the decision.
"District Attorney Castor cautions all parties... that he will reconsider this decision should the need arise," he wrote in a press release. "Much exists in this investigation that could be used (by others) to portray persons on both sides of the issue in a less than flattering light."
Castor did not immediately return a call Saturday, after CNN reported that he sent an email to his successor last fall explaining the agreement with Cosby's attorneys.
Castor mounted an unsuccessful campaign against Steele to return to office last fall. His decision not to charge Cosby was an issue in the race.
CBS affiliate KYW reported Cosby's defense lawyers filed a motion Tuesday to remove Steele from the case and have the charges dropped, citing the alleged 2005 agreement.
Steele told the station his office was not surprised by the motion. Steele said his office will not try a case in the court of public opinion, but rather in a court of law, so when they file a response, he'll let it speak for itself.
In Cosby's deposition, unsealed last year, the TV icon and champion of family values detailed his romantic interest in Constand, who is gay; his pursuit of other young women during his long marriage; and his use of quaaludes in the 1970s as a seduction tool.
He said that on the night in question, he gave Constand wine and pills before performing a sex act. He called it consensual. She said she was drugged and violated.
Cosby settled the lawsuit soon after giving his deposition.
Steele considered the deposition testimony along with the avalanche of new accusers making similar claims as he weighed the decision to charge Cosby before the 12-year statute of limitations expired this month.
According to Troiani, Cosby could have invoked his Fifth Amendment constitutional right against self-incrimination not to answer some questions at the deposition. But a jury could have made "a negative inference" about the decision if the case went to trial, she said.
The Feb. 2 hearing was initially scheduled as a preliminary hearing to determine if Steele has enough evidence to send the case to trial. But a judge has agreed to instead hear arguments on the defense motion to dismiss. His lawyers will also attack the 12-year delay to file charges and Steele's plan to call other Cosby accusers to show a pattern of behavior.