(Corrects Jan 22 story to remove name of court official from reporting credits. No change to text)
By Jon Herskovitz
AUSTIN, Texas, Jan 22 (Reuters) - A Mexican national convicted for the 1994 slaying of a Houston police officer was executed by lethal injection in Texas on Wednesday, ending a capital murder case that put him at the center of a diplomatic dispute.
Edgar Tamayo, 46, who was denied an 11th-hour stay of execution by the U.S. Supreme Court, was pronounced dead at 9:32 p.m. local time (0332 GMT) at a state prison in Huntsville, Texas, according to officials at the Texas Department of Criminal Justice.
The Mexican government had called on Texas to halt the execution, calling it a violation of international law, and U.S. Secretary of State John Kerry had asked Texas Governor Rick Perry to consider a stay.
Tamayo was convicted of shooting Houston police officer Guy Gaddis to death in 1994. Gaddis had arrested him on suspicion of robbery.
While handcuffed in the police car, Tamayo pulled a pistol that had gone unseen and shot Gaddis, 24, three times in the back of the head. Tamayo kicked open a window and ran away from the car but was arrested again a few blocks from the scene.
The Mexican government contends Tamayo was not informed of his right to diplomatic assistance in the case, a guarantee enshrined in an international treaty known as the Vienna Convention on Consular Relations.
In 2004, the United Nations' International Court of Justice ordered the United States to reconsider the convictions of 51 Mexicans, including Tamayo, who had been sent to death row without being informed of their consular rights.
Two from that group have previously been executed. Tamayo, who was in the United States illegally at the time of his arrest, became the third.
HOPING FOR A MIRACLE
As Tamayo's last chance for a reprieve slipped away, anguished relatives gathered at his parents' home in Miacatlan in central Mexico, huddling next to radios listening for news from the United States and praying for a miracle.
A crowd of nieces and nephews erupted in sobs when they heard about the Supreme Court decision.
"This pains us so much. We kept holding onto hope," said Karen Arias, one of Tamayo's nieces.
In a statement on Sunday, Mexico's foreign ministry said, "If Edgar Tamayo's execution were to go ahead without his trial being reviewed and his sentence reconsidered ... it would be a clear violation of the United States' international obligations."
Last month, Secretary of State Kerry urged Governor Perry, a foe of the Obama administration, to reconsider Tamayo's execution because it could make it more difficult for the United States to help Americans in legal trouble abroad.
On Wednesday, the State Department said it has been in communication with Texas throughout the process. Texas argues it is not bound by the International Court of Justice ruling.
"Mr. Tamayo was convicted of killing a police officer," State Department spokeswoman Marie Harf told a news briefing on Wednesday.
"It's not that we don't take that seriously. It's that we take seriously our obligations to uphold consular access for folks incarcerated here because we go all over the world and ask other countries to do the same thing and apply those same obligations when our folks are incarcerated overseas," she added.
The case has drawn attention from around the world. Tamayo said his family had received letters of support from at least 67 countries.
Back in his native town of Miacatlan, relatives professed their belief in Tamayo's innocence.
"He was like any other guy, a bit crazy yes, feisty, but not to the point of killing someone," said his cousin Kenia, a housewife, declining to give her surname.
A U.S. federal judge in Austin, Texas, on Tuesday rejected a request to delay the execution brought on Tamayo's behalf, saying Texas was operating within its rights.
Tamayo became the fourth person put to death in the United States this year and the first in Texas.
Texas has executed 508 prisoners since the reinstatement of capital punishment by the U.S. Supreme Court in 1976, the most of any U.S. state. (Additional reporting by Liz Diaz in Miacatlan, Sandra Maler in Washington, Gabriel Stargardter and Julia Symmes Cobb in Mexico City.; Editing by Eric Walsh and Lisa Shumaker)