Hour of Fear(1986)

In São Paulo, Alberto is an insane and sadistic man that kills women, and lives with his mother that covers all his mess. When he kills his mother's employee Eliana, stabbing her in the bathtub, they bury her in the backyard of their house. Eliana's fiancé unsuccessfully seeks her out and when Alberto's mother advertises that she needs a driver, he applies for the job to sneak around the real estate trying to find Eliana.