PHILADELPHIA — An ex-prosecutor is expected to testify that he promised Bill Cosby would never be charged over a Pennsylvania sex-assault complaint, but a judge must decide if that constitutes an immunity deal.

Then-District Attorney Bruce Castor will be a defense witness at a Feb. 2 hearing to determine if the case is thrown out.

The defense argues that prosecutors who arrested Cosby last month unfairly used his deposition testimony from the accuser’s 2005 lawsuit against him. Castor supports their position, but District Attorney Kevin Steele says there’s no evidence of an immunity agreement.

– From news service reports