I can't think of the name of this movie...?

Question

Basically, It starts with a guy in school. His teacher told him to take a little break..

then he thinks there's a killer out to get him. He thinks the killer is a kid he had locked into a house.. or something when he was younger. Basically he thought he killed the kid, but assumed the kid got out and was trying to kill him now that he was older... then he also had a female friend and a cop or detective or whatever she was to help him find the person who was trying to kill him. The killer also killed his dog in one scene. In the end of the movie you find out the killer and his female friend are both just parts of his imagination. Split personalities. I didn't like the movie, but It's bothering me that i can't think of the name of it... i hope someone out there can help me think of the name... i think i also remember in one scene the "killer" left a gun in the guy's book.

oh, and i remember his brother was "special" and his mom and dad had bunch of old newspapers.. and tried to teach him as a child a "fake reality".

Answer 1

Took me awhile to recall the name!! Could see everything you decribed playing in my head. :-)

Thr3e (2006)

Answer 2

Yeah, other answer is right.. Thr3e starring Mark Blucas (not sure I spelled his last name right.. he played Riley on Buffy the Vampire Slayer)

http://www.youtube.com/watch?v=RdAw98ZYVkk
(oddly enough, the trailer is better than I remember the movie being)