The attorney now representing former Oklahoma City pharmacist Jerome Ersland says he will file an appeal by the beginning of October.
A jury convicted Ersland last year for shooting and killing one of two masked teenagers who tried to rob Reliable Pharmacy in south Oklahoma City.
One of the teens was released from prison last week.
Prosecutors charged Ersland with murder, because after shooting and incapacitating 16-year-old Antwun Parker during the robbery, Ersland shot Parker five more times.
Don Franz is a fellow pharmacist who has visited Ersland in prison. Franz says he's confident Ersland will win his appeal.
"You really don't know what you do in a situation like that, and you are confronted and your adrenaline is high. People who have been Monday night quarterbacking haven't been in those shoes," Franz said.