"What if your brother shagged a witch?" he asked with confusion, thinking that was what she was concluding. "Well, he isn't exactly unfamiliar with our side of the wall, so to speak, as he is your brother. It may be entirely possible that he might meet a witch at a Muggle establishment. Many Half-bloods and Muggleborns have no aversion or fear of exploring the Muggle world, and may in fact find it necessary due to familial obligations."
He cocked his head. "You don't believe this witch might actually have something to do with his death, though. Do you? I can't imagine why, unless she were either highly disturbed, or a former Death Eater, but as far as I know, they have all been captured and sent to Azkaban for their crimes."