AKPOS QUESTION!!!

AKPOS QUESTION!!! I know u'r brilliant but Let me see how smart you are; Mr Emeka was found murdered on 19-6-2011 (Sunday Afternoon) inside his house, his wife called the police,they asked everyone around a question Police: where were you when his death happened?. WIFE: I was sleeping upstairs when the murder took place COOK: I was cooking in the kitchen HOUSE GIRL: I went to take the children from school. GARDENER: I was cutting the flowers at the backyard. GATEMAN: Oga sent me to buy newspaper for junction. After listening to their answers, the police arrested the murderer. Who was the murderer then?