Who killed Mr Desmond Inyang?

I know you are brilliant for sure, let me how smart you can be in answering this my question.

Mr Desmond Inyang a native of Calabar was found murdered in a cold blood on 09/06/13 (on Sunday afternoon) right in his sitting room.
The police were called to investigate his death, the police said they will be interrogating his household in order for them to uncover his death.
The police asked the man's wife where she was when the murder took place, she told the police that she was sleeping upstairs when the incident happened, the put the same question to the gardener, he said that he was busy cutting the flowers in the garden, the house girl was asked too who killed her oga, she said she went to pick the children from the school...while the cook also said that she was busy at the kitchen preparing food for her master...the gate man answered his question to the police that, as at the time the incident happened, oga sent him to buy sunday news paper. After listening to their answers, the police arrested the murderer.

 Who was the murderer??#sherlockholmestinz:-)