The US state of Missouri Wednesday executed its sixth inmate this year, using a lethal injection against a convicted triple murderer and meth dealer, who still maintained his innocence.
After multiple appeals including to the Supreme Court, John Middleton, 54, was declared dead at 7.06pm (local time) in Bonne Terre, said Missouri penal system spokesman Mike O'Connell.
The lethal injection of pentobarbital immediately followed a green light from the US Supreme Court and was over after eight minutes after it was administered, according to a court spokesperson.
"You are killing an innocent man" Middleton said in his final statement, according to prison authorities.
Middleton's execution occurred 19 hours after it was initially scheduled, following last-minute court proceedings.
In one appeal to the Supreme Court, his lawyers had argued that investigators built their case around an "invented" story by two drug dealers.
Middleton was sentenced to death in 1997 for the killing of two men on June 10, 1995 and another nearly two weeks later on June 23. Prosecutors say Middleton feared they might tell police he was a meth dealer.
However, a scientific expert has since revised the date of the third homicide to one day later, when Middleton was behind bars.
Middleton's lawyers also argued that he was incompetent to be executed. The inmate was a methamphetamine user with a history of psychiatric problems, according to an appeal filed with the Supreme Court.
Middleton's death marks the sixth execution so far this year in Missouri. Only Florida and Texas, with seven each, have put more people to death in 2014.
A total of 25 people have been executed across the United States over the same period.
His lethal injection follows a botched execution in Oklahoma on April 29, when Clayton Lockett, a convicted killer and rapist, was put to death in a process that took 43 minutes, well over the usual time of a little over 10 minutes.
The episode triggered a hot debate on lethal injection, and executions scheduled in its aftermath were suspended during a brief period that lasted until June 18, when executions resumed with Florida and Missouri putting to death one man each. – AFP, July 17, 2014.