Just a note to Joe'smom, if you see one in the basement, they are probably all over. We have lived in the country for many years and occasionally have a mouse problem. It has been my experience that there are usually more than one--I think they bring their friends. lol I have had cats all these years and occasionally they catch one and leave it on the floor--present, I guess, but even the cats get tired of them. I would set traps, I think there are live traps if you can't bear to kill them.
Sue