Yes, the secondary characters barely have any presence in the film. But perhaps the director had that intention from the beginning by focusing all the attention on the pair of detectives with different views and thoughts about the world and the killer. Still, I give it that perfect rating, it's more because of the ending, oh my God, an ending that tears your soul to pieces, yes. I wish Hollywood would release more movies with tragic, shocking, and thought-provoking endings like this one nowadays.

Thank you so much for your comment.