My guess, no direct evidence against him.
I agree.
My guess, no direct evidence against him.
I hope if they do know who it is it was an ex-con and they were able to take him off the street on parole violation like Ricci but there was no one like Mohl with Ricci to make it necessary for them to make it public. Thus they could keep him locked away until they either find Elizabeth or her body is found and they can continue gathering evidence.