McAlester, Oklahoma – Oklahoma resumed carrying out executions by lethal injection on Thursday after a six-year hiatus.

Death row inmate John Marion Grant, who was convicted of murder, died by lethal injection at the Oklahoma State Penitentiary in McAlester, according to the Department of Corrections.

Grant was the first convicted Oklahoma inmate to be put to death since the practice was halted in 2015 after several botched lethal injections, according to The Oklahoman newspaper.

He reportedly died strapped to a gurney while vomiting and convulsing from the first of three drugs given him. A trial is scheduled for February to determine whether the method is even constitutional.

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The execution followed last-minute legal wrangling.

The US Supreme Court ruled that the lethal injection could go ahead on Thursday after Grant and high-profile death row inmate Julius Jones were initially given stays of execution Wednesday by the 10th US Circuit Court of Appeals in Denver.

Grant (60) was sentenced to death in 1999 for killing an employee in a prison cafeteria, a crime he committed while doing jail time.

Earlier this week, Oklahoma's Department of Corrections reiterated its intention to resume executions.

"The Department of Corrections has addressed concerns regarding carrying out the death penalty and is prepared to follow the will of the people of Oklahoma, as expressed in state statute, and the orders of the courts by carrying out the execution of inmates sentenced to death by a jury of their peers," Director Scott Crow said.

According to the Death Penalty Information Center, the next two executions in Oklahoma are scheduled for November 18 and December 9.

While some states have abolished or suspended the death penalty by moratorium, it remains in effect in 27 of the 50 US states.