Exquisite Corpse (2010)

A medical student (Steve Sandvoss) is working on a research project and discovers that he is able to reanimate recently-deceased mice. He takes a break from his work to go on a trip with three friends. He admits to his friend Sophia (Nicole Vicius) that he loves her – but shortly after this she falls into a nearby lake and drowns. Using the methods from his research project he is able to revive her, but the process requires that he extract the hormone Oxytocin from a recently-dead corpse. He murders two women, and attempts to murder a third, in the process of keeping Sophia alive. His actions arouse the suspicion of his friends and the campus police. In a twist at the end of the film, Sophia remembers the circumstances of her death, which changes the audience’s perceptions of the actions of one of the main characters in the story

Source: TMDb