No, lol, he never killed anyone! At least not as far as I knew while dating him. This "encounter" happened at his/his parents' place, they were sharing the same building as it was divided into upstairs and downstairs.
Upstairs, so I was told, was sometimes visited by my boyfriends dead grandfather. He died in the same house years before. I'm not too sure about the authenticity of these stories but they seem to follow your "normal" haunting stereotype if you will, TV turn on/off on their own, pictures would fall down on their own account and apparently the grandfathers chair, a type of rocking chair would sometimes move. I never actually witnessed any of this though and none of these events were ever of a scary nature or had a bad feel about them otherwise, I think, the family would have moved! Who knows though, maybe my boyfriends grandfather was trying to tell me something.....hmm, maybe thats why that relationship didn't last :-p