Missouri executes Ernest Johnson for 1994 triple murder

(CNN) Missouri executed death row inmate Ernest Johnson on Tuesday after the US Supreme Court rejected a petition earlier in the day that had sought to delay it, citing an intellectual disability.

Johnson -- who was convicted of robbing a gas station and murdering three clerks nearly 27 years ago -- was pronounced dead at 6:11 p.m. CT after the administration of a lethal injection, according to Karen Pojmann, communications director for the Missouri Department of Corrections.

The petition from Johnson's lawyers, which was submitted to Justice Brett Kavanaugh, argued that the 61-year-old had "presented overwhelming evidence" of his intellectual disability.

"This Court should stay Mr. Johnson's execution so that his petition for certiorari can be fully and fairly considered by this Court. There is no state interest in executing people with intellectual disabilities. The balance of equities weighs in Mr. Johnson's favor," the application added.

But the Supreme Court's denial mirrored the Missouri Supreme Court's May opinion declining to stop his execution. The Missouri Governor's Office said in a news release on Monday that "Mr. Johnson's claim that he is not competent to be executed has been reviewed and rejected by a jury and the courts six different times, including a unanimous decision by the Missouri Supreme Court."

"The state is prepared to deliver justice and carry out the lawful sentence Mr. Johnson received in accordance with the Missouri Supreme Court's order," Republican Gov. Mike Parson said.

The US Supreme Court had previously ruled against Johnson in May, when he had sought to have his execution carried out by firing squad over fears that the state's lethal injection protocol would likely produce excruciating seizures because of his brain tumor. Johnson suffered from epilepsy as a result of the tumor and his lawyers argued that his condition would be exacerbated if he were executed by pentobarbital, a class of drugs known to produce seizures.

Johnson, in a handwritten last statement shared with members of the media on Tuesday, said in part: "I am sorry and have remorse for what I do." He also said he loved his family and friends and thanked his lawyer and those who had prayed for him.

According to a Gallup poll published in 2019, a majority of Americans -- 60% of those polled -- said they supported life imprisonment without parole as punishment for murder over the death penalty. It was the first time in at least 30 years that most Americans had said they favored a life sentence, Gallup said.