Apparent plot hole in S.3?

I am having trouble linking the incident where Saga's mentor, Hans, is "rescued" by the person that later turns out to the killer they are after. He would have to have known who it was that kidnapped Hans and where he was being held, and I saw nothing in the story that would allow him to have this info. In fact the police got a lucky clue as to who kidnapped Hans, but they did not know where he was being held. Unless I missed it, there has to be an explanation such as he stumbled across the kidnapping, and followed him to the kidnappers lair. But if that was the case, then this raises the question why didn't he just steal Hans from the kidnapper when he was absent.