its sunday and a woman reports her husband murdered. an investigator  comes and interviews the house hold (there is a maid, pool boy, personal  trainer, cook, and butler.) each gives what they were doing that the  time of the murder, the maid was getting the mail, the pool boy was  cleaning the pool, the personal trainer was working out, the cook was  cooking in the living room butler was dusting the living room... the  investigator instantly knew who did it and arrested the culprit. who was  it and how did he know?