One of the drugs the state was set to use last month in Warren Hill's scheduled execution had expired two weeks before he was supposed to die, records show.

The Department of Corrections tried to keep the execution on track by changing its procedures from using three drugs to only one, a barbiturate. That decision, however, became the basis for a stay issued by the Georgia Supreme Court less than two hours before Hill was to die for a 1990 murder.

Hill's execution is now on hold at least until November when the justices have said they will hear lawyers' arguments as to whether the state's Administrative Procedures Act requires 30 days of public comment before Corrections can make the change.

In an email Thursday, the Department of Corrections said: "The unavailability of pancuronium bromide was a factor in the decision to change Georgia's execution protocol but it was not the overriding concern."

DOC said there were alternatives to pancuronium bromide but the agency decided — the day before the scheduled execution — to switch to one drug instead of three after reviewing expert testimony, court decisions and the experiences of other states.

The agency's said it had been considering the change for a year, since it was forced to replace sodium thiopental with pentobarbital because of a shortage of that drug.

When DOC announced it would be the eighth state to use only one lethal injection drug, it said the revised protocol would let it "continue to proceed with court-ordered executions with the most responsible and professional manner."

The July 17 announcement also said DOC was rescheduling the executionof the mentally disabled Hill, who murdered fellow inmate John Handspike at the Lee Correctional Institution. DOC then moved the 52-year-old man's execution to July 23. It was subsequently stayed by the courts.

Documents obtained under the Georgia Open Records Act show the agency's supply of the paralytic pancuronium bromide, the second drug administered in the three-drug series, had expired on July 1. The DOC's supply of the sedative pentobarbital and potassium chloride, the final drug that stops the heart, were current.

Usually the potency of out-of-date drugs diminishes, said Randall Tackett, professor at the University of Georgia School of Pharmacy. If a condemned murderer is not completely paralyze, Tackett said, there could be a response to the injection of the potassium chloride, which can be extremely painful, even though sedated.

Richard Dieter of the Washington-based Death Penalty Information Center said a paralyzing drug like pancuronium bromide is used because it "freezes the muscles. But it's more for the sake of those viewing executions, that it not appear to be disruptive, violent or painful in any way." It is not clear how the Georgia prison system decided on pentobarbital.

According to 2,237 pages the Department of Corrections provided the AJC, there were no meeting notes, calendar entries or internal communications that reflected internal discussions of changing the lethal injection protocol in the months and years before July 17.

"This further proves that there are significant problems when a system is shrouded in secrecy," said Sara Totonchi, executive director of the Southern Center for Human Rights. "If we are going to have the death penalty, then we certainly need to know all of the facts before an execution is carried out."

The only related records were both dated July 17.

A one-page "staff action memorandum" announced the new procedure and noted an evolving national trend away from the three-drug method and for the use of a single drug.

"Competent medical experts have testified that the use of a single drug pentobarbital execution process will result in the rapid and painless death of the inmate," the memo said. "The department is committed to carrying out the order of the court in the most responsible and professional manner possible."

Also among the information was an 11-page document outlining the new, single-drug protocol.