If so, it would still be a trial for the murder of two women; doubt he can claim accident in both cases. Anyway, I just don't see his lawyer letting it get to the stage of showing where Mickey is, without some guarantee. As much as we'd like to think so, defense attorneys hearts are not with the victim. He/she would need to have their client protected. Taking a huge risk, if he intends to go to court on two murder charges, IMO, and claim the second one was an "oops".
JMO:
I wish we knew more about Lisa's case, evidence and how they expect to tie it in. Because we have many missing pieces it's hard to guess what the defense attorney could have in mind. The plan could be to say it was an accident with Mickey and that Lisa died of a drug overdose & he had nothing to do with it. Or he was with her when she died and frightened so he hid her body. Lisa does have a history of drugs and CP a history of drug overdoses/deaths.
Now if he confessed or if they found bindings of any sort with her remains, or pictures of her bound or deceased or personal belongings it would be harder for the defense to try to say BSL was not guilty.