What do i do about a stalker?

this guy just shows up at my house and starts shoveling snow, one morning i was hiding and not answering my door because it was him when he opened the doorand started fixing it, i now lock it at all times even putting a board up at it. the thing is he has about 3 personalities he goes from baby talk to real loud and gruff. i have a real good sixth sence and i do feel that he is trying to get at me. i never dated him and i have told him i am not his girlfriend now or do i ever want to be he gets real loud and then days later will call me back with this strange sweet baby talk. i never let him think i want him i have told him i dont. his wife died of a brain anuerism about 15 years ago. he said sometimes he had to hit her to get her under control. i want nothing to do with this wierdo but he hasn't done enough to call the cops. he also told me that he hit his son in the face when he was smaller and was turned into the cops by the childs school. the kid is in a wheel chair and has cerebral palsey. i really wonder in my heart if he killed his wife it just all seems strange to me. what can i do.