"The sentence of John Marion Grant has been carried out. The time of death is 4:21 pm [CDT]," the official said on Thursday evening.
Grant's execution is the Oklahoma's first execution of an inmate in six years.
Earlier in the day, the US Supreme Court issued an order overruling a stay on execution of two Oklahoma death row inmates by the Tenth Circuit Court of Appeals, allowing for the execution of one of the men on Thursday evening.
John Grant and Julius Jones were initially part of a lawsuit filed against the state of Oklahoma for its death penalty policy, challenging the state’s use of the drug midazolam as an effective way to reduce pain for the necessary length of time during executions.