I am thinking there is another law enforcement jurisdiction involved, that is aware of what is going on and has issued the FBI an ultimatum.
Higher than that. I think it is the Joint Chiefs of Staff. They like us have had enough of this corrupt government. They have the muscle to pull this off. They have info which proves obstruction of justice from the POTUS on down plus a corrupt Congress which will not do its oversight. I bet they have threatened him to do his job and nail everybody or they are going to take action which will yield very, very unpleasant results. Better to face civilian justice than UMCJ type of justice system.