Kay also felt that was Mama's way of telling her that Michael was indeed the killer.

Also in the novel, the police show up at Kay's house, looking for Michael and questioning her about his whereabouts, sure that he has been in touch with her or told her where he was going. When she says that she doesn't know, and wouldn't tell if she did, they threaten to tell her parents that she and Michael were sleeping together (rather frowned upon in the 1940's).

If the police suspected Kay of knowing Michael's whereabouts and went so far as to travel to New Hampshire to check her out, Tom's course of action was the wisest one, for Michael's safety.