In his last minutes, Humberto Leal repeatedly said he was sorry and accepted responsibility. "I have hurt a lot of people. ... I take full blame for everything. I am sorry for what I did," he said in the death chamber.
"One more thing," he said as the drugs began taking effect. Then he shouted twice, "Viva Mexico!"
"Ready warden," he said. "Let's get this show on the road."
He grunted, snored several times and appeared to go to sleep, then stopped all breathing movement. The 38-year-old mechanic was pronounced dead at 6:21 p.m., 10 minutes after the lethal drugs began flowing into his arms.
|Mexicans burning an American flag|
Leal's uncle Alberto Rodriguez criticized the U.S. justice system and the Mexican government and said, "There is a God who makes us all pay."
Leal was sentenced to death for the 1994 murder of 16-year-old Adria Sauceda, whose brutalized nude body was found hours after he left a San Antonio street party with her.
She was bludgeoned with a piece of 30- to 40-pound chunk of asphalt.
The court rejected the request 5-4. Its five more conservative justices doubted that executing Leal would cause grave international consequences, and doubted "that it is ever appropriate to stay a lower court judgment in light of unenacted legislation."
"Our task is to rule on what the law is, not what it might eventually be," the majority said. The court's four liberal-leaning justices said they would have granted the stay.
The Obama administration took the unusual step of intervening in a state murder case last week when Solicitor General Donald Verrilli Jr. joined Leal's appeal, asking the high court to halt the execution and give Congress at least six months to consider Leahy's bill.
|President Obama appeals for mercy for Mexican killers|
Some also warned his execution would violate the treaty provision and could endanger Americans in countries that deny them consular help.
Measures similar to Leahy's have failed at least twice in recent congressional sessions. The Texas Attorney General's office, opposing the appeals, pointed to those failures in its Supreme Court arguments and said "legislative relief was not likely to be forthcoming."