Plus with the money he got from Wayne, he can probably afford a good lawyer.
What money did he get from Wayne??
In other news, I really want to see reformed!Riddler interact with Spoiler, since her father worked with him before he reformed and she died went to Africa. And IIRC there was a story where she confronted Riddler after her dad died (mind you, I'm told he's not dead anymore) and asked about him.