HUNTSVILLE — Michael Sigala was on probation for robbery and allowed to leave a Dallas-area substance abuse treatment center for the day to look for a job. Instead, he violently ended the lives of a newlywed Brazilian couple and ended up on death row.

Sigala, 32, was set for execution Tuesday evening for the death of Kleber Santos, 28, a Brazilian engineer whose wife also was killed in an attack nearly a decade ago at their Plano apartment.

Sigala would be the third Texas inmate to receive lethal injection this year and the first of four scheduled to die this month in the nation’s most active death penalty state.

The U.S. Supreme Court last week refused to review his case and no new appeals were in the courts Monday.

Sigala, of Plano, was condemned for the fatal shooting of Santos, whose job brought him to Texas in January 2000, a month after he was married. His wife, Lilian, remained in Brazil to continue her veterinary studies at the University of Sao Paulo and was visiting her husband during a school break that August.

Evidence showed the 25-year-old woman was raped and also fatally shot several hours after her husband was killed. Their wedding rings were among items taken in the attack. Sigala also was charged with her slaying but was not tried.

Their bodies were found by a neighbor after Santos failed to show up at work as a software developer for a cellphone manufacturer in nearby Richardson. His wife’s hands were tied with telephone wire. A phone cord also was around her neck.

“It was pretty sad, especially when you think of your husband being killed in front of you, then you’re dragged off, your clothes taken off, being tied up and who knows what,” Debbie Harrison, a Collin County assistant district attorney who prosecuted the case, said last week.

Sigala was arrested about two months later after a camera taken from the apartment was found at a pawn shop in Arlington, some 30 miles to the southwest. That led investigators to the couple’s wedding rings, which had been pawned in Dallas.

Sigala declined to speak with reporters as his execution date neared. In a videotaped statement to police following his arrest, he initially denied any involvement but later said he shot the couple in self-defense because Santos struck an accomplice of his with a baseball bat. Authorities found no evidence of a second attacker.

“I freaked out,” Sigala told detectives. “I didn’t mean to hurt nobody.”

He contended he and the friend, who he knew only as Billy, went to the apartment to sell Santos some heroin, but authorities found no evidence Santos or his wife ever used drugs. A toxicology report also found no illegal drugs in either victim. Sigala’s DNA was found in semen on the floor next to a bed.

“He was in the apartment a very long time,” Harrison said. “He sat down and watched TV for a while. He cleaned the apartment immaculately. Everything was wiped down.”

It’s uncertain why that apartment was chosen for the attack.

Another convict, Adam Lay, was implicated in the pawning of the stolen items but not charged in the slayings. He received 35 years in prison for violating probation from a previous aggravated robbery conviction and doesn’t become eligible for parole for another eight years.

At Sigala’s trial, defense attorneys argued unsuccessfully for a life prison sentence, saying Sigala’s drug use and poor family life as he was growing up contributed to his criminal activity.

When he was arrested, Sigala was on 10 years probation for a 1999 robbery conviction. He’d already spent 30 days in jail, then was assigned for a second time to a drug treatment center in Wilmer, south of Dallas, as part of his probation. On the day of the slayings, he was out on a one-day pass to look for work. Getting a job was among the requirements for a permanent release.

He’d earlier violated probation for illegal drug use. As a juvenile, he was on probation for theft, then received jail time for marijuana possession and another jail stint for theft. At age 13, he was arrested for burglary. A year later, he was banned from Plano public school grounds for carrying a gun.

Records showed the 11th-grade dropout once worked as a security guard at Lone Star Park, a Dallas-area horse track.

Next week, an Indiana man, Joshua Maxwell, 31, was set to die for the abduction, robbery and fatal shooting Rudy Lopes, an off-duty Bexar County Sheriff’s Department sergeant, in 2000.