Edgar Tamayo, 46, received a lethal injection Wednesday night for the January 1994 fatal shooting of Officer Guy Gaddis, 24.
Asked by a warden if he had a final statement, he mumbled "no" and shook his head. As the lethal dose of pentobarbital began taking effect, he took a few breaths and then made one slightly audible snore before all movement stopped. He was pronounced dead 17 minutes after the drug was administered, at 9:32 p.m. CST.
The execution, the first this year in the nation's most active death penalty state, was delayed more than three hours while the U.S. Supreme Court considered last-ditch appeals.
Tamayo never looked toward Gaddis' mother, two brothers and two other relatives who watched through a window.
"He's a coward, just like when he shot my brother in the back of the head, and he died a coward," Glen Gaddis said.
Several dozen police officers and supporters of the slain patrolman revved their motorcycles outside the prison before witnesses were allowed into the death chamber. Tamayo selected no witnesses of his own.
"A little bit of my shredded heart is feeling better," the officer's mother, Gayle, said.
The execution came after the U.S. Supreme Court and lower federal courts rejected last-day appeals and Texas officials spurned arguments that Tamayo's case was tainted because he wasn't informed, under an international agreement, that he could get legal help from the Mexican consulate after his arrest in the officer's slaying.
Attorneys had also argued unsuccessfully that Tamayo was mentally impaired, making him ineligible for execution, and that the state's clemency procedures were unfair.
The Texas Board of Pardons and Paroles rejected Tamayo's request for clemency on Tuesday.
"It doesn't matter where you're from," said Lucy Nashed, spokeswoman for Gov. Rick Perry. "If you commit a despicable crime like this in Texas, you are subject to our state laws, including a fair trial by jury and the ultimate penalty."
Tamayo's lawyers, Sandra L. Babcock and Maurie Levin, issued a statement after the Supreme Court's ruling, saying Perry and Attorney General Greg Abbott "ignored promises they made to our nation's leaders that they would ensure review of Mr. Tamayo's consular rights violation."
"The execution of Mr. Tamayo violates the United States' treaty commitments, threatens the nation's foreign policy interests, and undermines the safety of all Americans abroad," Babcock and Levin also said.
The Mexican government earlier this week said it "strongly opposed" the execution.
"The issue of fundamental importance in this case is the respect for the right of access to protection provided by our consulates to Mexicans abroad," Euclides Del Moral Arbona, a director in the Mexican Ministry of Foreign Affairs, told reporters outside the prison.
Gaddis, who had been on the force for two years, was driving Tamayo and another man from a robbery scene when the officer was shot three times in the head and neck with a pistol Tamayo had concealed in his pants. The car crashed, and Tamayo fled on foot but was captured a few blocks away, still in handcuffs, carrying the robbery victim's watch and wearing the victim's necklace.
Mexican officials and Tamayo's attorneys contend he was protected under a provision of the 1963 Vienna Convention on Consular Relations. Legal assistance guaranteed under that treaty could have uncovered evidence to contest the capital murder charge or provide evidence to keep Tamayo off death row, they said.
Records show the consulate became involved or aware of the case just as his trial was to begin.
Secretary of State John Kerry previously asked Abbott to delay Tamayo's punishment, saying it "could impact the way American citizens are treated in other countries." The State Department repeated that stance earlier Wednesday but had no immediate comment following the execution.
Another of Gaddis' brothers, Gary, said it was "unfortunate this has become a political event."
"But we're here to remind the public who the true victim is in this crime and to warn the public that John Kerry has no right to try to change the locks of the Supreme Court and turn the keys over to the international community," he said.
Tamayo was in the U.S. illegally and had a criminal record in California, where he had served time for robbery and was paroled, according to prison records.
At least two other inmates in circumstances similar to Tamayo's were executed in Texas in recent years.
He was among more than four dozen Mexican nationals awaiting execution in the U.S. in 2004 when the International Court of Justice in The Hague, Netherlands, ruled they hadn't been advised properly of their consular rights.
The Supreme Court subsequently said hearings urged by the international court in those inmates' cases could be mandated only if Congress implemented legislation to do so. That legislation has not been passed.
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