Donald Newbury, 52, became the third member of the group known as the "Texas 7" executed for the fatal shooting of 29-year-old Aubrey Hawkins, a police officer who interrupted the fugitives' robbery of a sporting goods store on Christmas Eve in 2000.
The slaying occurred 11 days after the convicts escaped. The gang was captured a month later in Colorado.
Asked to make a final statement, he mumbled: "I would. That each new indignity defeats only the body. Pampering the spirit with obscure merit. I love you all. That's it."
He was pronounced dead 11 minutes later, at 6:25 p.M. About two dozen police officers stood at attention outside the Huntsville prison. Several supporters of the slain officer were on motorcycles outside, and as Newbury was taking his final breaths, the roar of revving engines could be heard inside the death chamber.
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The punishment was carried out after Newbury lost a last-day appeal to the U.S. Supreme Court. His attorneys had argued previous lawyers were deficient and courts did not provide adequate money for a defense expert to illustrate how Newbury's abusive childhood influenced his violent behaviour.
Two days later, Rivas and Newbury held up a store, taking electronics including police radio scanners.
"Rivas was the leader and would do the talking and Newbury was one of the guys standing with the gun and threatening everybody," said Toby Shook, the former Dallas County assistant district attorney who prosecuted both. "Rivas was using him as his muscle."