answer this one first and you win the ultimate prize!!...................................A rich man was found murdered on Sunday morning. His wife immediately called the police. The police questioned the wife and staff and got these alibis:
The Wife said she was sleeping.
The Cook was cooking breakfast.
The Gardener was picking vegetables.
The Maid was getting the mail.
The Butler was cleaning the closet.

The police immediately arrests the murderer. Who is it and how did the police know who I was?

very simple is this one