The pictures in the house/spoilers

I think that Harry was obsessed with finding the person who murdered his wife to the point where he lost touch with reality. He was teetering on the brink of insanity before the cops came to him with a picture of the man who did it. He had already been suspecting innocent people in the mall before the cops told him that. So, after that, he lost it and began his journey into madness. He had been imagining his wife walking next door to that house the same way he was imagining her throughout the movie. So, there was no real purpose for going over there to find any clues. He began imagining his murder theory at that point. There were no negatives or pictures...or if there were...they were no one significant. He went to that town, Morristown, and may have interacted with people but he imagined Remr, his wife, quinn and the theory that he killed his wife. Maybe remr symbolized how he wished his life had been if his wife had lived and had their baby...and maybe that's why the room he met Remr in was the opposite of 305, where he was staying. He imagined being with him in 503 and didn't kill anyone. The cops confirm this at the end of the movie when they say there there was no crime. the whole scene involving the three cops talking about their "killing off the bad cops" story was imagined.