A condemned killer whose use of a smuggled cell phone prompted a lockdown of the entire Texas prison system has received an execution date.

Texas Department of Criminal Justice officials say they've received legal paperwork that sets May 20 as the date for the lethal injection of 31-year-old Richard Tabler.

He was convicted of fatally shooting two men in Killeen on Thanksgiving weekend five years ago. He achieved more recent notoriety for his threatening calls - using an illegal cell phone - to state Sen. John Whitmire.

Those calls resulted in a sweep of all Texas prisons for contraband and uncovered hundreds of illegal phones, phone equipment and weapons.