A juvenile services worker says a man convicted of killing a North Texas pastor had been committing crimes since he was a teenager.The testimony came Monday during the punishment phase in Steven Lawayne Nelson's trial.Nelson was convicted earlier Monday of capital murder for killing Rev. Clint Dobson at Arlington's NorthPointe Baptist Church. He also beat the church secretary before stealing her car.State juvenile services worker Mary Kelleher says Nelson was 14 when he was sent to a juvenile prison for unauthorized use of a motor vehicle and burglary. Other testimony revealed he assaulted a jail guard.Nelson is facing the death penalty or life in prison without parole. Defense attorneys say the 25-year-old had serious family issues, including setting his mother's bed on fire at age 3.