After the US Supreme Court cleared the way for the execution on Thursday, Oklahoma killed a man for the 1998 stabbing death of a prison cafeteria worker, the state's first lethal injection after a six-year moratorium.

After being strapped to a gurney inside the execution chamber and given a lethal injection of three chemicals, John Marion Grant, 60, was certified dead at 4:21 p.m.

Since a series of botched lethal injections in 2014 and 2015, Grant was the first inmate to be killed. Witnesses allege he dragged Gay Carter, a prison cafeteria worker, into a mop closet and stabbed her 16 times with a handmade shank while serving a 130-year jail sentence for many violent robberies. In 1999, he was sentenced to death. Grant's bid for clemency was denied twice by the state.

The execution was set to take place on Thursday after the US Supreme Court, in a 5-3 ruling, overturned stays of execution issued by the 10th US Circuit Court of Appeals on Wednesday for Grant and another death row inmate, Julius Jones.

Oklahoma had one of the busiest execution chambers in the country until 2014 and 2015, when difficulties forced a de facto halt. When prison officials realized they had received the wrong deadly medication, Richard Glossip was just hours from from being executed in September 2015. It was later discovered that in January 2015, the same incorrect medication was used to execute a convict. Clayton Lockett struggled on a gurney before dying 43 minutes after his lethal injection in a botched execution in 2014.