He hasn't been arrested or charged and he isn't being held so what is there to release him from? According to the state attorney reviewing the case she doesn't need a grand jury to decide to charge him and take him to trial. She should likewise have the authority to say "there's no case here" and close the matter. She is the one who was assigned by the Governor to make that decision. It would be a slap in her face, and the Governor's, if she decided "no case" and someone else stepped up and said "we still need a grand jury." Who would have the authority to do that? It's the state attorney's job to make that recommendation.
That was if she decided to arrest him.