being as it's a riddle. the answer is obviously sunday in this horrible riddle. there's not enough information to come to a proper conclusion. He was FOUND on sunday.. ok? when did he DIE? what if the maid forgot it was sunday and just went to check the mail. there's too many factors to just key out one person for checking the mail and going OH! IT WAS THEM! how bout they do some real investigative police research and find a murder weapon or evidence. Brainless cops.