A North Texas man whom experts for both prosecutors and defense attorneys had said was intellectually disabled became the 600th person executed in Texas since 1982, put to death Thursday evening for the killing of a retired 77-year-old college professor.

Edward Busby, Jr. was pronounced dead at 8:11 p.m. local time following a lethal injection at the state penitentiary in Huntsville, hours after a divided Supreme Court lifted a stay over his disability claims. The execution followed a series of last-minute legal efforts by Busby's attorneys in a bid to spare his life after the nation's high court lifted a stay hours earlier.

Busby was condemned for the suffocation death of Laura Lee Crane, a 77-year-old retired professor from Texas Christian University who prosecutors say was abducted from a grocery store parking lot in January 2004 and left to suffocate in the trunk of her car with duct tape wrapped around her face.

Busby appeared extremely contrite when asked by the warden if he had a final statement, repeatedly apologizing and asking for forgiveness – before the drugs began flowing.  

Busby's execution had been in doubt after the 5th U.S. Circuit Court of Appeals last week issued a stay to further review his claims of intellectual disability. But the U.S. Supreme Court overturned the stay on Thursday at the request of the Texas Attorney General's Office. Three of the nine justices on the high court would have allowed the stay to remain, including Justice Ketanji Brown Jackson.

"In capital cases, we rarely intervene to preserve life. I cannot understand the Court's rush to extinguish it, much less in the circumstances of this case," Jackson wrote in a dissent.

After the Supreme Court's decision, Busby's lawyers filed another stay request with the 5th Circuit on Thursday evening, but it was swiftly denied.

The Supreme Court in 2002 barred the execution of intellectually disabled people. But it has given states some discretion in determining which disabilities qualify.

His attorneys argued Busby is barred from being put to death because a defense expert, as well as one hired by the Tarrant County District Attorney's Office, which prosecuted the case, has both found he is intellectually disabled.

The district attorney's office had recommended that Busby's sentence be reduced to life in prison. But the trial judge in Busby's case disagreed with the findings of intellectual disability and, in 2023, upheld the death sentence.

In a statement on Wednesday, the district attorney's office said it requested Thursday's execution date because "under current case law, we believe Mr. Busby is not intellectually disabled. We agree with the Texas Attorney General's handling of the case."

In December, the Supreme Court heard arguments in a case out of Alabama that could change how courts may consider the cumulative effect of multiple IQ scores in assessing intellectual disability.

The Texas Attorney General's Office had asked the U.S. Supreme Court to lift the stay, arguing Busby's claims of intellectual disability are "meritless" and based on "conflicting evidence." The attorney general's office is also arguing that Busby's claims of intellectual disability should not be reviewed because they are "time-barred" and previous similar appeals have been rejected.

"Busby has litigated his (intellectual disability) claim many times over. He was not entitled to another bite at the apple," the attorney general's office said.

In a concurring opinion that had temporarily blocked the execution, 5th Circuit Judge James Graves Jr. said: "The medical community's consensus here is that Busby is intellectually disabled and ineligible for execution."

Two other prior execution dates for Busby had been delayed by the courts.

Abraham Bonowitz, executive director of Death Penalty Action, a national anti-death penalty group, criticized the attorney general's efforts to have the execution go forward without a review of the merits of Busby's intellectual disability claims.

"The merits of this case are significant," Bonowitz said. "How can anyone claim this is fair due process?"

Prosecutors have said Busby and his co-defendant, Kathleen Latimer, abducted Crane in her car from a Fort Worth grocery store parking lot and later put her in her vehicle's trunk as they drove around. Prosecutors said she died in the trunk after suffocating from having 23 feet (7 meters) of duct tape wrapped over her entire face, covering her mouth and nose.

Busby was arrested in Oklahoma City, driving Crane's car, and led authorities to her body in Oklahoma, just north of the Texas border.

After his arrest, Busby told investigators that Latimer was the person who had pushed him to abduct Crane, restrain her with the tape, and that he "never meant for her to get hurt or anything." Latimer remains in prison after receiving a life sentence for murder.