A Texas inmate who had been described as intellectually disabled by civil rights advocates was put to death Thursday, officials said.
Robert Ladd, 57, was pronounced dead at 7:02 p.m. at Texas State Penitentiary in Huntsville, according to a spokeswoman for the state Department of Criminal Justice.
The U.S. Supreme Court on Thursday denied his attorney's request for a stay of execution.
Ladd was convicted of killing Vicki Ann Garner of Tyler, Texas, in 1996, beating her with a hammer, robbing her and setting her body on fire, correctional records say.
In his final statement, Ladd apologized to Garner's family and asked them to find solace in something other than his death.
"I am really sorry. Please don't have hate in your heart. I really feel like this," Ladd said, according to a transcript of his statement. "I hope you can find peace in your heart and happiness. A revenge death won't get you anything."
Ladd was nearly put to death in 2003, but a federal court agreed to hear evidence that he was mentally impaired, according to a report in the Associated Press.
Ladd had an IQ of 67, and his pending execution had drawn stark criticism from civil rights advocates.
"Texas aggressively pursued Mr. Ladd's execution, despite the fact that our constitution categorically prohibits the use of capital punishment against persons with intellectual disability," Brian Stull, a senior staff attorney with the American Civil Liberties Union, said in a statement. "Mr. Ladd, whose IQ was 67, was executed because Texas uses idiosyncratic standards, based on stereotypes rather than science, to determine intellectual disability."
A Texas Department of Criminal Justice spokeswoman described the execution as "routine" and said Ladd did not appear to suffer.
Ladd had previously served prison time after he pleaded guilty to killing Vivian Thompson and her two children, Latoya and Maurice, in 1978. He was sentenced to 40 years in prison but paroled after serving 16 years. He killed Garner two years later.
Ladd's IQ score comes from a test administered while he was in a Texas juvenile corrections facility. A psychiatrist there noted Ladd suffered from "mental retardation, mild to moderate," records show.
The Texas Court of Criminal Appeals defines a significant "subaverage intellectual functioning ... as an IQ of about 70 or below."
Ladd's execution is the second this week involving a convicted killer with purported intellectual disabilities.
On Tuesday, Georgia executed Warren Lee Hill, a former petty officer with the Navy who had an IQ of 70.
Hill had been sentenced to life in prison for the murder of his girlfriend in 1986, and he was convicted in the killing of a fellow inmate four years later. Hill's attorneys had argued that he had the mental capacity of an 11-year-old child.