He will serve life in prison without parole.
In June, 14 year old Alyssa Wiles was found dead in her home.
Police say Wiles' father found her body in a pool of blood when he returned home from work.
Her former boyfriend, Michael Anthony Ray, was charged as an adult for first degree murder for stabbing her to death.
Police say he confessed to the murder and said he was angry she had broken off their relationship the day before
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