If you all really listen to CR's recording in the camera laying next to him. The camera really belongs to Kate, when I really listen to the recording. Kate was actually killed by CR because she was being followed by Slenderman. He starts blaming your character and set the woods on fire and eventually killed himself from killing Kate and trying to kill you. At the end, Kate's ghost attacks you and giving off the same effect as Slenderman.
Slender: The Arrival © Blue Isles