Washington (AFP) - Texas on Wednesday executed a man who murdered three family members, following a trial in which a bailiff wore a tie depicting a syringe in an apparent reference to the lethal injection procedure.
Robert Sparks, 45, was pronounced dead at 6:39 pm local time (2339 GMT).
He was sentenced to death in 2008 for stabbing to death his wife as well as his two stepsons aged nine and 10, before raping his 12- and 14-year-old teenage stepdaughters in their Dallas home in the middle of the night.
Shortly after the murders, he claimed he had been protecting himself from his wife, who he said was trying to poison him.
His lawyers appealed his conviction to the US Supreme Court, saying that he was mentally disabled and suffering from psychosis, rendering him ineligible for the death penalty.
They also stressed that his trial had been marred by the bailiff's tie, saying it could have influenced the jury.
The Supreme Court rejected the appeal just hours before the execution.
Justice Sonia Sotomayor acknowledged the bailiff's choice was "deeply troubling," but said there was not sufficient evidence that the jury had seen the tie.
She urged judges to "intervene in future cases" by removing such clothing -- or the people wearing it -- from the courtroom.
Sparks is the seventh person executed in Texas and the 16th in the United States since the start of the year.