Bloodlust (1976)

A deaf and dump clerk is an excellent employee and is bullied by his envious co-workers. In his private life, he is a man with a childhood trauma since his abusive father caused his disability with his beatings. He collects dolls and has a crush on his neighbor that loves to dance. Out of the blue, he feels attraction for blood and necrophilia. He goes to the morgue in the cemetery to drink blood from fresh corpses, mutilating the bodies and writing "Mosquito" on the wall. When his neighbor dies, he murders living people to drink their blood.