Officials in Alabama have halted the lethal injection execution of a prisoner on death row because they couldn't find a vein before the midnight deadline.
Alabama corrections commissioner John Hamm said the decision to call off the scheduled execution of Alan Miller was made after it became clear they could not get the process under way in time.
The last-minute reprieve came nearly three hours after the US Supreme Court cleared the way for the execution to go ahead.
"Due to time constraints resulting from the lateness of the court proceedings, the execution was called off once it was determined the condemned inmate's veins could not be accessed in accordance with our protocol before the expiration of the death warrant," Mr Hamm said.
The execution team had began the process of trying to establish intravenous access, but he did not know for how long.
The execution was abandoned at around 11.30pm on Thursday - half an hour before the state's death warrant was set to expire.
Miller, a delivery truck driver, was convicted of killing three men in a workplace shooting rampage in 1999 near Birmingham, Alabama.
The 57-year-old had opted for nitrogen hypoxia instead of lethal injection due to a fear of needles, but his lawyers said officials lost his paperwork.
The technique is legally available to him, but has never been used in the United States.
It would cause death by forcing the inmate to breathe only nitrogen, depriving them of the oxygen needed to maintain bodily functions.
When Alabama approved nitrogen hypoxia as an execution method in 2018, state law gave inmates a brief window to designate it as their execution method.
Miller said he turned in the documents four years ago selecting nitrogen hypoxia, putting the papers in a slot in his cell door at the Holman Correctional Facility for a prison worker to collect.
His execution by any other means was blocked by a federal judge on Tuesday after finding it was "substantially likely" that Miller "submitted a timely election form even though the state says that it does not have any physical record of a form".
However, justices at the Supreme Court - in a 5-4 decision - lifted an injunction that had blocked the lethal injection execution from going forward.