In the movie Secret Window, Mort's dog Chico is found dead stabbed with a screwdriver and Mort deduces that Shooter have killed the dog (as a letter was attached to the dog's body). But later in the movie, it is revealed that its Mort himself who was acting Shooter's part.
And also, for the other murdered people (Greenleaf, the detective, etc), it can be said the Shooter/Mort killed them as they stood in his way. But why kill he dog? He was not harm to Shooter/Mort's intentions or whatsoever..
So why did the dog have to die? Is is in some way connected to the movie's storyline or just put there to confuse the viewer?