Apparently search warrants aren't needed in this town

Who, the priest? He saw him through the window, dead or unconscious. That's probable cause. If you're referring to Mrs. Jones, he heard movement in the house after he was knocking. I took it to mean that he wasn't going in to search with her as a suspect in mind, as much as to see if she was alright. Especially given the fact that he just discovered her "nephew" had been tortured and Keller was at large. He could have had a hunch Keller was there given the circumstances. Aside from that, I'd say he was pretty flexible with the rules.