My theory of the movie (spoilers obviously)

Watching the movie, actually seen it twice but I don't remember anything from when I watched it the first time 10 years ago except that I thought it had a creepy amosphere but that the ending didn't give away any real answers

Anyways

On the rewatch I initially thought that John Turturro himself could be the killer and that he couldn't live with that so his mind subconsciously blocked out any memory of him killing her (possibly because she was cheating on him, there were some hints I felt in the movie that that could have been the movie)

However once James Remar admits to having killed an innocent woman (Turturros wife) that idea fades away a bit

And with the ending of him being in the hospital and with the cops saying there was nothing to suggest that a crime was commited in the motel, despite him confessing to killing James Remar (something that isn't shown on screen)

You start to wonder, if he can hallucinate about killing James Remar what's not to say that he hallucinated his whole meeting of him and his confession as well?

So my theory turns into that John Turturro got so obsessed with finding clues to his wife's killer that he went blind (figuratively speaking) and a little crazy with the hallucinations and stuff, and that in the end when he throws away the pictures he realises that he might not ever find out who the killer was and that he just have to accept that and move on or it will drive him even more towards lunacy

Many murders are not solved and many familymembers are left wondering why, and that is what I think the movie is trying to portray what that can feel like, you aren't meant to find out who the killer is in the movie cause that's not what this movie is about

And I think had it been my initial thought that Turturro was the killer that he'd be quite upset about the realisation of that where as here in the end Turturro looks somewhat releaved like he is able to move on

If your dream is shattered, pick up the glass