bill cosby*Bill Cosby is reaching into the past to get the sex assault case against him dismissed.

The BBC cites an email CNN saw that details how a prosecutor promised that Cosby’s infamous deposition in Andrea Constand’s 2005 civil case would not be used to bring criminal charges against him.

The deposition, which is the basis of the aggravated indecent assault charge for Cosby, finds that although the embattled comedian admitted to drugging women during sexual encounters, he says the action was done by mutual consent.

Regarding Constand, Cosby confessed to giving Ms Constand wine and pills but stated that she consented to take them. In addition to drugging women, Cosby went on to admit that he paid off other women to keep them quiet.

At that time, Former Montgomery County district attorney Bill Castor was the person in charge when Constand sued Cosby in a civil sex assault trial in 2005, after no criminal charges were brought. The entertainer ultimately settled the case for an undisclosed sum.

CNN notes that Castor had agreed that the civil deposition Cosby made in the case would not be used to bring criminal charges against him. Countering Castor is the current DA, Kevin Steele, who stated that there isn’t any evidence of a signed immunity agreement regarding Cosby. Castor goes on to point out that such a piece of information would have had to go through agreed channels.

Nevertheless, Cosby’s lawyers are determined to use the immunity claim to get the case against their client dismissed. According to the Associated Press, Constand’s lawyer mentioned that she never knew of such an agreement.

Three months before criminal charged were filed against Cosby Castor wrote to his successor, Risa Vetri Ferman, saying, “I can see no possibility that Cosby’s deposition could be used in a state criminal case, because I would have to testify as to what happened, and the deposition would be subject to suppression.

“I cannot believe any state court judge would allow that deposition into evidence, he continued. “…Knowing this, unless you can make out a case without that deposition and without anything the deposition led you to, I think Cosby would have an action against the County and maybe even against you personally.”

As it stands now, it looks like Cosby’s lawyers will call Castor to testify in the case when they try to get the aggravated indecent assault charge dismissed at a hearing scheduled for Feb. 2.

Cosby’s lawyers efforts to get the case dismissed is the latest development to occur since dozens of women spoke out against the funnyman with accusations of sexual assault going all the way back to the ‘70s. With the statute of limitations running out on the majority of the claims, Constand’s case against Cosby is the only one that resulted in one charge being brought against him.

The decision to bring criminal charges against Cosby was made by Steele in December before the statute of limitations in Constand’s case ran out in January.