ATLANTA (AP) — Georgia officials waffled on whether to proceed with an execution when the lethal injection drug was discovered to have a cloudy appearance, according to court documents, and one expert said their decision to postpone it was the right move.

The execution of Kelly Renee Gissendaner was delayed late Monday night. A day later, they decided to temporarily halt executions until they could more carefully analyze the pentobarbital, which is supposed to be clear.

"If it's a solution that's supposed to be clear and it's not clear, it should never be injected," said Michael Jay, a professor at the University of North Carolina's Eshelman School of Pharmacy. "So they did the right thing by not injecting it."

The cloudy drug bolstered death penalty opponents, who have been vocal in their opposition after three botched executions in other parts of the country.

Gissendaner, who was convicted of murder in the February 1997 slaying of her husband, had originally been set for execution last week on Feb. 25, but it was postponed because of a threat of bad weather.

Attorneys for Gissendaner said in a filing with the U.S. Supreme Court that a lawyer for the state called them around 10:25 p.m. Monday to say the execution would be postponed several days because the state's pharmacist had looked at the drug an hour earlier and determined it was cloudy.

The state's lawyer called back about five minutes later to say the prison wasn't sure which drugs they had checked, "this week's or last week's," and that they were considering going forward, the filing says.

The lawyer called a third time, saying "this particular batch (of drugs) just didn't come out like it was supposed to" and they weren't going to proceed, according to the court filing.

About 11 p.m., the state told reporters an independent lab checked its potency and it was acceptable, but it later appeared cloudy and the execution was postponed "out of an abundance of caution."

The back and forth was detailed in Gissendaner's emergency motion for a stay.

Corrections spokeswoman Gwendolyn Hogan said "there was never any confusion within the department about the drugs which were to be used," but also indicated the department was not part of the conversations between the attorney general's office and defense attorneys.

Georgia Attorney General Sam Olens said in a statement it is "essential that executions are carried out in a constitutional manner" and that he approved of the decision to temporarily suspend executions.

The cloudiness could be contamination by bacteria or some impurity, said Jay, the pharmacy professor.

If the particles were big enough, they could clog blood vessels when injected or could lodge in the lungs, Jay said. It could also make the drug less potent, making an inmate very sleepy but not kill them, he said.

Compounded drugs have a shelf life of 30 days, Jay said. Corrections officials declined to say when the department obtained the drug or when it was set to expire.

Georgia and other death penalty states have bought execution drugs from compounding pharmacies in recent years after pharmaceutical companies stopped selling to U.S. prisons. And many of them have adopted laws to hide the identity of their drug providers, saying those laws are necessary to protect their suppliers and maintain a source of the drugs. Critics say executions should be as transparent as possible.

The cloudy drug "raises significant concerns about Georgia's ability to carry out executions in compliance with the Constitution, but we don't know what really happened," said Megan McCracken of the University of California, Berkeley, School of Law's Death Penalty Clinic.

"Because of the secrecy surrounding Georgia's procedures, it is impossible to say if this is indicative of a larger problem," she said.

Richard Dieter, executive director of the Death Penalty Information Center, which tracks data on executions, said he's never heard of an execution being halted at the last minute because of a problem with the drug itself.

Missouri and Texas are also actively using compounded pentobarbital in a one-drug formula for executions, and South Dakota has also used this method, McCracken said.

Other states have been using a three-drug combination starting with the sedative midazolam. But executions in those states are mostly on hold pending a U.S. Supreme Court ruling in an Oklahoma case sparked by a botched execution there.

Prosecutors said Gissendaner repeatedly pushed her on-again, off-again lover Gregory Owen to kill her husband, Douglas Gissendaner. Owen ambushed her husband while she went out with friends, forced him to drive to a remote area and stabbed him multiple times.

Owen and Gissendaner then met up and set fire to the dead man's car. Both initially denied involvement, but Owen eventually confessed and testified against his former girlfriend. Owen is serving a life prison sentence and is eligible for parole in eight years.

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