Teacher's Pet (2000) on Netflix

Plot summary

Debbie Strand, a psychopath held in an institution for the criminally insane, gets free when a female orderly tries to attack her. On the road she is picked up by a teenage girl, who dies during the encounter, and Debbie takes her car and her name. Posing as the daughter of a wealthy man, she arrives on the campus where the girl had enrolled and moves into a room with Laney, a naive student she soon influences. There she meets Sam Deckner, the high school teacher she once obsessed over, now a writing professor whose interests seem to match hers. Her fixation revives, and she begins to kill anyone she believes stands between them.