A death row inmate has been executed for the drug-related murders of four people more than 30 years ago.
Arthur Brown Jr, now 52, was condemned for the June 1992 deaths in a Houston home during a drug robbery - including shooting dead a pregnant 19-year-old woman.
Authorities said Brown was part of a ring that shuttled drugs from Texas to Alabama and had bought drugs from Jose Tovar and his wife, Rachel.
He was put to death shortly after 12.30am UK-time.
Brown was convicted of killing 32-year-old Jose Tovar; his wife's 17-year-old son, Frank Farias; 19-year-old Jessica Quinones, the pregnant girlfriend of another son of Rachel Tovar, and 21-year-old neighbour Audrey Brown.
All four had been tied up and shot in the head. Rachel Tovar and another person were also shot but survived.
Jessica Quinones had been nine-months pregnant and had named her unborn daughter Alyssa.
Maricella Quinones, Jessica Quinones' older sister, said: "I don't see how anybody could have just killed a pregnant woman and then made her suffer so much. It's just beyond words."
One of Brown's accomplices in the shootings, Marion Dudley, was executed in 2006. A third partner was sentenced to life in prison.
Brown, from Tuscaloosa, Alabama, had long maintained another person committed the killings.
About three hours before Brown's scheduled Thursday evening execution at the state penitentiary in Huntsville, Texas, the U.S. Supreme Court declined an appeal from his lawyers.
His attorneys had asked the high court to halt the execution, arguing that Brown is intellectually disabled.
The high court has prohibited the death penalty for the intellectually disabled.
Virgin CEO Richard Branson also launched a petition to stop the execution on the basis of Brown's alleged intellectual disabilities.
Branson wrote: "If the State of Texas gets its way, Mr. Brown, a Black, intellectually disabled man, will be killed this Thursday in the execution chamber at Huntsville Prison, following a death sentence he was given for four drug-related murders committed in 1992.
"I hope prosecutors and courts will stop this execution. Harris County’s District Attorney has recently released new, exculpatory evidence suggesting that other people, not Mr. Brown, committed the murders – supporting what he’s been saying for the entire 30 years he has been incarcerated: “I am innocent.”
In a petition to the Supreme Court, Brown's attorneys wrote: "Mr. Brown's intellectual limitations were known to his friends and family. ... Individuals that knew Mr. Brown over the course of his life have described him consistently as `slow'."
Brown's attorneys have previously filed other appeals that have been rejected by lower courts. They have argued he is innocent and that a witness actually implicated another suspect. They also claim Brown's conviction was tainted by racial bias, alleging one of the jurors decided he was guilty because of his race. Brown is a Black man.
A judge in Houston on Tuesday denied a request by Brown's attorneys for DNA testing of evidence that they said could exonerate their client.
Josh Reiss, chief of the Post-Conviction Writs Division with the Harris County District Attorney's Office in Houston, called Brown's last-minute appeals a delay tactic.
Reiss said school records submitted at Brown's trial showed while the inmate was initially thought to possibly be intellectually disabled in the third grade, by ninth grade that was no longer the case.
The prosecutor also said Brown's claims of innocence are problematic as the other suspect alleged to be the killer was found by investigators to not have been in Houston at the time.
"It was an absolutely brutal mass murder. ... These families deserve justice," Reiss said.
Maricella Quinones, 52, said her sister was an innocent victim who wasn't aware the Tovars were dealing drugs from the home. She said her mother also blames the Tovars for what happened.
"My mother's not the same since my sister passed away," Maricella Quinones said.
Maricella Quinones described her sister as a "very loving, caring person" who had looked forward to being a mother. She said her family would likely never get closure.
"We lost two persons. Alyssa never got a chance at life," she said.
Brown's execution is the second of two in Texas this week.
Another inmate, Gary Green, was executed Tuesday for fatally stabbing his estranged wife and drowning her 6-year-old daughter in a bathtub. Brown would be the fifth inmate in Texas and the ninth in the U.S. put to death this year.
Brown was one of six Texas death row inmates who are part of a lawsuit seeking to stop the state's prison system from using what they allege are expired and unsafe execution drugs.
Despite a civil court judge in Austin preliminarily agreeing with the claims, four of the inmates have been executed this year.
