An Alabama man convicted of murdering a woman during a robbery is to be executed on Thursday barring a last-minute intervention by the US Supreme Court or the governor of the southern state.
Willie Smith, 52, is to be put to death by lethal injection at 6:00 pm Central Time (2300 GMT) at a prison in southwest Alabama.
Smith has been on death row for 30 years after being convicted of the 1991 murder of 22-year-old Sharma Ruth Johnson in Birmingham.
Smith was granted an 11th-hour stay of execution in February after the Supreme Court ruled that barring a priest from being by his side during his death was unlawful.
Prison officials have since said they would allow Smith's pastor to be present but his lawyers have been seeking to halt the execution on other grounds.
They have argued that Smith is intellectually disabled and he has not been allowed to choose the manner of his execution.
In 2018, Alabama approved the use of nitrogen gas as a means of execution in addition to lethal injection.
Because of his mental disability, Smith -- who has an IQ of around 70 -- could not understand that he was able to choose this method of execution, his lawyers said.
Capital punishment has been abolished in 23 US states, while three others -- California, Oregon and Pennsylvania -- have observed a moratorium on its use.