So, the reason that Batman & Robin were after Filipe is that he attacked his girlfriend. Robin makes it clear that he has a problem with guys beating up women (maybe something to do with his sick mother and his criminal father?). However, this guy is the son of a diplomat, so he doesn't stay in jail long at ALL and the girlfriend is soon found dead. Robin blames Filipe (even though there's no proof, of course) and takes off...
That's an understatement.
Filipe kidnapped this girl, beat the crap out of her, and repeatedly raped her. Then, when it was clear that he was going to get away with that because of diplomatic immunity, he phoned her and cheerfully threatened her, implying that he would rape her again, until she couldn't take it anymore and hung herself. Jason, who had taken care of the girl from the beginning and done his best to comfort her, was the one to find her corpse when he went to her place to try and console her.
Frankly, if Jason really killed the guy, I'd hardly blame him.