<P> During the next loop, she relays her story to Carter, who suggests that she take advantage of the loop in order to figure out who her killer is . She spends the next loops trailing several suspected classmates, all of which end in her murder as she is stalking the current suspect . </P> <P> On the next loop after being bludgeoned by a baseball bat from her previous death, Tree passes out shortly after waking up . She awakens in the hospital where she learns she has retained damage from her other murders and is growing weaker . Tree escapes the hospital room only to be chased by her killer until she manages to flee in Butler's car . While driving, she is pulled over by a police officer and volunteers to be arrested in order to be spared . However, the killer runs down the officer and sets her car on fire, burning Tree to death and sending her through another loop . </P> <P> Waking up in Carter's bed again, Tree convinces Carter of her predicament by showing that she holds foreknowledge of the day's events . Tree admits to Carter she doesn't like who she's become; she has also grown distant from her father ever since her mother passed away three years ago and that they had shared the same birthday . Tree catches a local news report on John Tombs, a serial killer who is being held in the hospital on her campus . Concluding that Tombs is her killer, Tree rushes to the hospital to warn of his escape . Tombs breaks free and nearly kills Tree, but Carter follows and rescues her . Unfortunately, Tombs snaps Carter's neck before chasing Tree to a nearby bell tower where she manages to subdue him with a crowbar . Realizing that Carter will remain dead if she doesn't restart the loop, Tree hangs herself from the tower . </P> <P> During the next loop, Tree goes around righting the various wrongs she has caused, ending her affair with Dr. Butler, finally meeting with her dad to resolve her inner grief, and resolving to be a kinder person . That night, she prepares to stop Tombs . He manages to get the upper hand on her until Tree utilizes a campus - wide blackout that occurs during her loops to disarm him and shoot him to death . Relieved to finally be free, she celebrates her birthday in Carter's room and eats the cupcake given to her by Lori . </P>

Who kills tree gelbman in happy death day