Susan blinked hard at the sharp and suspicious sounding 'why'. She let her nostrils flare just ever so slightly at having a question thrown back at her like that.
But she put on a smile. "There was a murder in Hogsmeade this past Friday, and a man who is under suspicion claims he was with you all evening." Her eyes left a lingering look that told her she could make one guess about what they were doing all night long. It probably wasn't needlepoint.
"You certainly aren't under any suspicion, if that's what you're worried about. I just need to know who you were with, and that will be the end of the matter."