I had the wrong answer, and now I don't know if I should feel relieved or dissapointed seeing that lots of you guys got it right. Seriously I didn't even think about the correct answer, but now when I look back at the question it was kinda obvious really.
No, it just means you're too founded in science to even think that way. Only someone who has a complete lack of understanding of basic scientific understandings like "correlation does not imply causation". Only someone who thinks correlation does imply causation would murder someone to make someone else appear again.
You could say that "well, he showed up at the mother's funeral, so he must be close to the family". The fact that the sister didn't know him proves he wasn't close to the family. It makes sense that either he was a friend of the mother only, not the family (maybe a friendly coworker or neighbor) or was just at the wrong funeral. In the case of the latter, the chances are small he'd appear again. In the case of the former he definitely wouldn't appear again.
In the end, the only scientifically sound explanation for what happened is old Andy's.