Michael Yowell, 43, told witnesses, including his daughters and his ex-wife, that he loved them.
"Punch the button," he told the warden.
He took several deep breaths, then began snoring. Within about 30 seconds, all movement stopped.
He was pronounced dead 19 minutes later at 7:11 p.m. CDT.
Yowell tried to delay his execution, the 14th this year in the nation's most active death penalty state, by joining a lawsuit with two other condemned prisoners that challenged Texas prison officials' recent purchase of a new supply of pentobarbital for his scheduled lethal injection.
The U.S. Supreme Court rejected the appeal minutes before Yowell was taken to the Texas death chamber Wednesday evening.
The prisoners argued use of the sedative could cause unconstitutional pain and suffering because the drug, replacing a similar inventory that expired at the end of September, was made by a compounding pharmacy not subjected to strict federal scrutiny. Texas, like other death penalty states, has turned to compounding pharmacies that custom-make drugs for customers after traditional suppliers declined to sell to prison agencies or bowed to pressure from execution opponents.
The lawsuit sought an injunction to delay the execution and gain more time to ensure "the integrity and legality" of the drug and be certain its use was within constitutional protections.
Attorneys for the inmates took the case to the U.S. Supreme Court after lower federal courts ruled that the drug appeared adequate and that the Texas Department of Criminal Justice did nothing wrong in acquiring it.
"Our baseline contention is we, the public, have to be concerned about transparency and accountability by a state agency that's carrying out the gravest of all possible duties," Maurie Levin, one of the inmates' attorneys, said.
Yowell's parents, John, 55, and Carol, 53, were found dead in the wreckage of their home following an explosion on Mother's Day weekend in 1998. Yowell's 89-year-old grandmother, Viola Davis, who was staying there, died days later of injuries suffered in the blast.
Yowell already was on probation for burglary and drug convictions. He was arrested on federal firearms charges and charged with his parents' slayings after authorities determined his mother had been beaten and strangled and his father was shot. Prosecutors showed John Yowell was killed when he caught his son stealing his wallet. Yowell then attacked his mother, opened a gas valve and fled. The home blew up.
"At some point he's looking his mom in the face, beating her and wrapping a lamp cord around her neck," Lubbock County District Attorney Matt Powell, who prosecuted the case, recalled Tuesday. "I think always there are some unanswered questions. You want to know how somebody is capable of doing that to their parents."
Evidence showed Yowell had a $200-a-day drug habit he supported by stealing. Evidence also showed he burned some of his bloody clothes and hid a blood-stained jacket and the murder weapon in the crawl space of a friend's house. Defense attorneys unsuccessfully tried to show Yowell was insane.
On Monday, the U.S. Supreme Court refused to review appeals that contended Yowell received shoddy legal help at his 1999 trial and in the early stages of his appeals.
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