The fact that a man had managed to acquire or use a house did not tell me who knew why he wanted it.

People processing a sale could have seen ordinary papers and an ordinary buyer.

Neighbors could have seen a vehicle, closed curtains, and a quiet woman.

I had.

What we knew about Derek’s behavior came from witnesses, physical evidence, records, and the woman and children he had kept there.

It did not come from a general rule that private people must be hiding something.

That distinction was important to me after a neighbor remarked that we should have known because the curtains were always shut.