Michael Rodriguez is the third of six surviving convicts who broke out of the prison to be convicted in the death of Officer Aubrey Hawkins.
Prosecutors said the 29-year-old rookie was shot 11 times and run over twice while trying to stop the seven inmates from robbing the Oshman's Sporting Goods in Irving on Dec. 24, 2000.
On Friday, the jury was to begin hearing witnesses in the punishment phase of the trial. Prosecutors are seeking the death penalty.
Two other inmates were convicted and sentenced to death for the slaying; three others also face capital murder charges.
The seventh inmate committed suicide when they were cornered by authorities in Colorado about a month after the escape.