Learn prospecting, where's Olf?

I want to learn about prospecting, and I've heard that the trainer is a guy named Olf, who used to be hold as a prisoner inside Don's house in Harbour Town, a coherence with the three-golden-bowls-quest I've heard. When you've done the quest you shoud be able to speak to Hernandez or something, but the thing is that I've done the quest but when I approach him he threatens to attack me, and I have no open quest that has anything to do with the bowls, Olf or Scurdo (Don's man in HT). How do I get to learn prospecting, considering my current situation?

Olf is first found sat on a bench, a prisoner in the Dons house, he will teach the prospecting skill right there and then if Hernandez is satisfied to release him. Much depends on the quest swing toward the Don or the Order, i gave the three golden bowls to Carasco instead of Scordo, Hernandez was happy with this and released Olf (but i still joined with the Don)

PS. I doubt it can be reversed unless you load an earlier save.

Olf sits in the rear on the second floor, near a window. Climb up on he roof in the back and into the window, quick couple steps to him and a conversation, then jump back out the window when done. Sometimes a guard up there, but often not.