Who is the Killer???

Riddle No.07  :-

One day a man was found dead in his house. When police inquired about it, his wife said, "I was asleep." 

The police officer then said to his wife, "Tell us everything you know." Then. 

The wife told police that the floor cleaner was cleaning, the cook was cooking, and the garden cleaner was cleaning the garden. Shortly afterwards, police arrested a one of them. Who is that????

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