Murder on the orient express, it's a classic i highly recommend. Or everything that was ever a book by agatha christie. 

L.A Confidential and also Who Framed Roger Rabit. 

I was also thinking about Insomnia, but in this movie you look at his cover, or trailer, and you know who the killer is. So maybe not the right one. 

There is also The Bone Collector. I never did like this movie, but other people did like it, so why not. 

The Name of the Rose, is awesome. Some people say its very borring, but i disagree.