Ramiro Hernandez-Llanas, 44, was lethally injected in the state's death chamber in Huntsville.
He was in the U.S. illegally when he was arrested for the October 1997 slaying of 49-year-old Glen Lich. Just 10 days earlier, Lich had given Hernandez-Llanas a job helping with renovations at his ranch near Kerrville, about 65 miles northwest of San Antonio, in exchange for living quarters.
Investigators said Hernandez-Llanas lured Lich from his house by telling him that there was a problem with a generator, then repeatedly clubbed him with a piece of steel rebar. Armed with a knife, he then attacked Lich's wife. She survived and testified against Hernandez-Llanas, who also had been linked to a rape and a stabbing.
Strapped to a gurney inside the death chamber, Hernandez-Llanas asked for forgiveness. He also said he was at peace and thankful for being able to see relatives, and he urged them not to be sad.
"I'm happy... I am sorry for what I have done," he said, speaking in Spanish during a nearly five-minute final statement. "I'm looking at the angel of God."
He raised his head from the gurney three times and blew three loud kisses toward a brother, a sister and two friends watching through a window. He also thanked prison officers and the warden.
"I say this with a lot of love and happiness: I have no pain and no guilt. All I have is love," he said.
As the lethal drug took effect, he snored loudly twice, then appeared to go to sleep. Within seconds, all movement stopped. He was pronounced dead 11 minutes later, at 6:28 p.m.
Lich's son, who also witnessed the execution, declined to speak with reporters afterward.
Hernandez-Llanas was the second Texas inmate to receive a lethal injection of a new supply of pentobarbital. Texas Department of Criminal Justice officials have refused to identify the source of the powerful sedative, contending secrecy is needed to protect the drug's provider from threats of violence from capital punishment opponents. The U.S. Supreme Court backed the state's position in a related case last week.
Texas and other states that have the death penalty have been scrambling for substitute drugs or new sources for drugs for lethal injections after major drugmakers many based in Europe with longtime opposition to the death penalty stopped selling to prisons and corrections departments.
Hernandez-Llanas' appeals were exhausted, and the Texas parole board on Tuesday refused to delay his death sentence or commute it to life in prison.
He was among more than four dozen Mexican citizens awaiting execution in the U.S. when the International Court of Justice in The Hague, Netherlands, ruled in 2004 that they weren't properly advised of their consular rights when arrested. A measure mandated by the U.S. Supreme Court to enforce that ruling has languished in Congress.
On Wednesday, the Mexican government's Ministry of Foreign Affairs released a statement condemning the execution.
"This is the fourth case of a Mexican being executed in clear violation of the judgment of the International Court of Justice," the ministry said. "The Government of Mexico expresses its most vigorous protest at the failure to comply."
But that issue never surfaced in Hernandez-Llanas' appeals, which focused primarily on claims that his mental impairment made him ineligible for the death penalty. Testimony from psychiatrists who said he was not mentally impaired and would remain a danger was faulty, his attorneys argued.
According to trial testimony, Hernandez-Llanas was arrested just hours after the attacking Lich and his wife. He was sleeping in the bed where he had wrapped his arm around the terrorized woman, who managed to wriggle from his grasp and restraints without waking him and call police.
Evidence showed Hernandez-Llanas was in Texas after escaping from a Mexican prison, where he was serving a 25-year sentence for a 1989 bludgeoning murder in Nuevo Laredo. He was linked to the rape of a 15-year-old girl and a stabbing in Kerrville. While awaiting trial, evidence showed he slashed another inmate's face with a razor blade. In prison, he was found with homemade weapons.
"This is exactly why we have the death penalty," Lucy Wilke, an assistant Kerr County district attorney who helped prosecute Hernandez-Llanas, said ahead of the execution. "Nobody, even prison guards, is safe from him."
Hernandez-Llanas was the sixth prisoner executed this year in Texas, the nation's busiest death penalty state.