A planned execution by lethal injection in the US state of Tennessee was halted at the last minute on Thursday after officials failed to establish a second intravenous line (IV) required by law, prison authorities said.
Authorities said one IV line had been inserted, but despite several attempts they were unable to find a suitable vein for the second line.
According to NBC News, a federal public defender said he had been taken "off the gurney" following the aborted procedure.
The inmate has spent more than 30 years in prison after being convicted, among other charges, of three murders. His lawyers had sought until the last moment to prove his innocence through DNA analysis.
"The State of Tennessee is currently torturing a man who maintains his innocence in the name of justice. This is not how our system is supposed to work," said counsel Melanie Verdecia.
US states individually decide whether to use capital punishment in their criminal justice systems. Twenty-three of 50 US states have abolished the death penalty, while several others no longer carry out executions in practice.
Tennessee has recently faced scrutiny over its lethal injection protocol, the most common execution method in the US. The state suspended all executions for three years after it emerged that officials had failed to properly test the drugs used in lethal injections.
Governor Bill Lee ordered a one-year postponement of Thursday's execution shortly after news of the halted procedure emerged, his office said.
Lee had rejected a clemency request from the inmate only days earlier.
