COLUMBIA, S.C. (AP) — South Carolina's prisons director said Wednesday that state's supply of a lethal injection drug is pure, its electric chair was tested a month ago and its firing squad has the ammunition and training to carry out its first execution next month in more than 13 years.

Corrections Director Bryan Stirling was ordered by the state Supreme Court to submit a sworn statement to the lawyer for Freddie Owens certifying that all three methods of putting a prisoner to death are available for his scheduled Sept. 20 execution.

Owens' lawyers have said they will review the statement, and if they don't think it is adequate, they will ask the state Supreme Court or federal judges to consider it.

It's one of at least two legal issues of contention between the state and Owens ahead of next month's execution date.

Owens has until Sept. 6 to decide how he wants to die, and he signed his power of attorney over to his lawyer, Emily Paavola, to make that decision for him. The state Supreme Court has agreed to a request from the prison system to see if that is allowed under South Carolina law.

The state suggested in court papers that the justices question Owens to make sure he understands the execution method choice is final and can't be changed even if he were to revoke the power of attorney.

The power of attorney was signed under the name Khalil Divine Black Sun Allah. Owens changed his name in prison but goes by his old name in his legal hearings with the state to avoid confusion.

In the sworn statement, Stirling said technicians at the State Law Enforcement Division laboratory tested two vials of the sedative pentobarbital, which the state plans to use for lethal injections.

The technicians told him the drug is stable, pure and under guidelines from other jurisdictions that use a similar method is potent enough to kill, Stirling wrote.

The state previously used a three-drug cocktail but those drugs expired, part of the reason no execution has been carried out in South Carolina since 2011.

Stirling released no other details about the drugs under the guidelines of the state's new shield law, which keeps secret the name of the supplier of the drug and anyone who helps carry out the execution. The law's passage in 2023 also helped restart executions so the state could buy pentobarbital and keep the supplier private.

The state's electric chair, built in 1912, was tested June 25 and found to be working properly, Stirling wrote, without providing additional details.

And the firing squad, allowed by a 2021 law, has the guns, ammunition and training it needs, Stirling wrote. Three volunteers have been trained to fire at a target placed on the heart from 15 feet (4.6 meters) away.

Owens, 46, was sentenced to death for killing convenience store clerk Irene Graves in Greenville in 1997. Prosecutors said he and friends robbed several businesses before going to the store.

One of the friends testified that Owens shot Graves in the head because she couldn't get the safe open. A surveillance system didn't clearly show who fired the shot. Prosecutors agreed to reduce the friend's murder charge to voluntary manslaughter and he was sentened to 28 years in prison, according to court records.

After being convicted of murder his initial trial in 1999, but before a jury determined his sentence, authorities said Owens killed his cellmate at the Greenville County jail.

Investigators said Owens gave them a detailed account of how he killed Christopher Lee, stabbing and burning his eyes, choking him and stomping him while another prisoner was in the cell and stayed quietly in his bunk. He said he did it “because I was wrongly convicted of murder,” according to a confession read by a prosecutor in court the next day.

Owens was charged with murder against Lee right after the jail killing. Court records show prosecutors dropped the charge in 2019 with the right to restore it around the time Owens exhausted his appeals for his death sentence in Graves' killing.

Owens has one more avenue to try to save his life: In South Carolina, the governor has the lone ability to grant clemency and reduce a death sentence to life in prison.

However no governor has done that in the state's 43 executions since the death penalty was restarted in the U.S. in 1976.

Gov. Henry McMaster said he will follow longtime tradition and not announce his decision until prison officials make a call from the death chamber minutes before the execution.

McMaster told reporters Tuesday that he hasn't decided what to do in Owens' case but as a former prosecutor he respects jury verdicts and court decisions.

“When the rule of law has been followed, there really is only one answer,” McMaster said.