Oklahoma Corrections Department officials used bottles labeled potassium acetate for the final drug during the lethal injection Jan. 15 — in violation of protocol, the records show. Officials were supposed to use potassium chloride to stop Warner's heart.

The wrong deadly drug was used to execute baby killer Charles Frederick Warner in January, records show.

The same wrong drug was delivered to corrections officials Sept. 30 for the scheduled lethal injection that day of another convicted murderer, Richard Glossip.

Oklahoma's governor, Mary Fallin, granted a last-minute stay after learning of the mix-up.

Attorney General Scott Pruitt then launched an investigation into the circumstances surrounding Glossip's execution. On Wednesday, he confirmed the investigation will cover any previous drug mistake.

“I want to assure the public that our investigation will be full, fair and complete and includes not only actions on Sept. 30, but any and all actions prior, relevant to the use of potassium acetate and potassium chloride,” Pruitt said.