Ruiz was condemned for the July 14, 1992, fatal shooting of 29-year-old Theresa Rodriguez, killed in the garage at her home as she was getting out of her car and with her husband, Michael, and his brother, Mark, at the scene.
"I didn't think I was going to get a stay," Ruiz told prison officials. "I guess you could say I'm happy."
Texas Department of Criminal Justice spokeswoman Michelle Lyons, who described Ruiz as "genuinely at a loss for words," said the prisoner "didn't seem like he had processed it yet.
"He apparently was expecting to go. He expected his execution to be carried out," she said.
Ruiz, who had a history of alcohol and drug dependency, implicated the brothers for hiring him for what authorities said was their plan to collect more than $250,000 in Theresa's life insurance.
The Rodriguez brothers eventually agreed to a plea deal, accepting life prison terms. But Michael Rodriguez later joined Ruiz on death row as one of the notorious Texas Seven, a group of inmates who escaped from a South Texas prison in 2000 and killed a Dallas-area police officer during a Christmas Eve sporting goods store holdup. He's awaiting execution and recently asked that all his appeals be dropped, but has no date for his lethal injection.
Ruiz's lawyers argued that a state-appointed lawyer in earlier appeals failed to identify Ruiz's substance abuse and poor childhood as mitigating evidence jurors should have been allowed to consider before they decided on a death sentence. A three-judge panel of the 5th Circuit court, in a 2-1 vote, said in granting the stay that it needed more time to review the case.
The Ruiz case illustrated what lawyers Morris Moon and Chris Gober contended was the state's "knowing and deliberate indifference to a system" that failed to permit a proper review of death row convictions.
The arguments focusing on what they argued was shoddy legal help during crucial initial appeals failed to convince the Texas Board of Pardons and Paroles and the Texas Court of Criminal Appeals.
The U.S. Supreme Court earlier this year refused to review his case.
"He's got rights but nobody ever talks about the victim and her rights because she's dead," said a disappointed Yolanda Dolmolin, the slaying victim's sister. "And all that's gotten lost in the last 15 years."
She and another sister and brother were among witnesses who had been waiting for several hours to see Ruiz die.
The shooting at the Rodriguez home in San Antonio came after Ruiz made two earlier unsuccessful attempts. After shooting her once in the head with a .357-caliber Magnum pistol, he ran to a car waiting for him on the street and drove off. Mark Rodriguez already had paid him $1,000, then gave him another $1,000 after the job was finished.
Joe Ramon, now 34, who accompanied Ruiz the night of the shooting, and Robert Silva, also 34, identified as the intermediary who put the Rodriguez brothers in touch with Ruiz, also wound up with life prison sentences.
Ruiz was arrested after a telephone tip to authorities and after Theresa Rodriguez's employer, the insurance firm USAA, offered a $50,000 reward for information about her slaying.
While in the Bexar County Jail awaiting trial, authorities believe Ruiz joined the Texas Syndicate, a notorious prison gang, and was involved in several disturbances resulting in assaults on officers and other inmates.
Scheduled to die next is Lonnie Johnson, 44, set for lethal injection July 24 for the shooting deaths of two Harris County teenagers and theft of their truck almost 17 years ago.