Yep, it's him. He was enraged because Eric finally gave in to his urges and molested a kid. "My site, my consequences," says Jake when he gets arrested. His anger seems to come as much from jealousy that Eric gave in. Unfortunately, Eric refused to tell Jake who the victim was. "You just killed the only person who knew who the victim was," an angry Olivia tells him.
Olivia holds a press conference with a picture of Eric to ask anyone who'd seen him around to come forward. She interviews five kids, all of whom saw Eric or talked to him, or took candy from him, but none of them were actually molested. Munch tells a despondent Olivia that the kid will turn up, but it's not much comfort to think that, since it's only because the abuse, as described on Pediaphax, was so awful that the victim will have too many problems for a parent not to know something's up. Yeah, thanks for the comfort, Munch.
So: Elliot gone, for who knows how long (back next episode?), and there's a horribly traumatized victim out there who may never get help. The only thing that saves things from being a complete downer is the abused woman from the opening segment shows up, bruised and bloody, and ready to give a statement. She doesn't want to die, she tells Munch. That's great. Because after this episode I feel like killing myself.