The Stalker by Susan K Droney
Jeremy Talbot is a lonely, troubled writer whose only friends are the demon voices he hears in his mind. In his senior year of college, a popular classmate Rebecca Walker takes pity on him and befriends him. His obsession with Rebecca begins, and leads him on a murderous rampage as he tries in vain to prove that the demons are wrong when they taunt him, declaring that she doesn't care for him. When Rebecca moves to Boston, Jeremy changes his identity and follows her and the murders that have plagued Pittsburgh end, but begin in Boston. As the police get closer to learning Jeremy's true identity, he finally puts his plan in motion to claim Rebecca for his own.