Acussed of rape by force but completely false accusations?

A member of my family has been wrongly accused of raping a 9 yr girl we all know he is innocent the ex got him arrested because he won't take her back..she is mentally unstable.. Havin said that What else does she need to do to keep him in jail after having put him in thereit cant be so easy just to show up to the PD and accuse someone of something worse than murder.. What kind of follow ups will she have to do? I mean I want to know what else to expect. We got a lawyer and she gives us hope but still I can't stay just waking around I do not want an innocent man to have to endure what sexual abusers go trough in jail that would totally destroy all of us around him. He is innocent plz help!