BILLINGS — A Billings teen has been sentenced to 70 years in prison for beating and stabbing his great-grandmother to death during an argument last summer.

Robert Alan Thompson learned his punishment Thursday after a 90-minute hearing that included testimony from his mother and two other relatives.

Deputy County Attorney Christopher Morris said that Thompson read a prepared statement and then directly addressed family members.

Morris said Thompson apologized, accepted full responsibility for his actions and asked for their forgiveness.

The argument with Shirley Lawrence started when she told him to get a job and that he was going to turn out like his father. After killing her, Thompson stole her car and drove to Denver, where he was arrested.