A Florida police chief and one of his officers are facing charges in the fatal shooting of a 73-year-old retired librarian during a citizen's academy "shoot/don't shoot" class last summer.

Fox 13 Tampa reports that Punta Gorda Police Chief Tom Lewis and Officer Lee Coel were arrested Wednesday following an investigation by the State Attorney’s Office.

Coel, 28, is facing a manslaughter charge that could put him behind bars for up to 30 years. Lewis was charged with culpable negligence, a misdemeanor.

The retired librararian, Mary Knowlton, was a volunteer in a role-playing exercise designed to show citizens what officers face in life-and-death situations, the station reported. Knowlton played a cop and Coel played a bad guy.

The station reports that Knowlton was hit with a live round from Coel’s gun, which should have been loaded with blanks. She was taken to a hospital where she died.

Defense attorney Jerry Barry said Wednesday that Coel didn't know the gun was loaded with live ammo.

"From the understanding we have of the facts, it’s a negligent act,” he says in a video posted on the Fort Myers News-Press website. “But the amount of negligence necessary to make it a criminal act is very high and I don’t see how the facts as we know them would amount to criminal negligence as opposed to simple negligence.”

Punta Gorda city manager Howard Kunik said Thursday that Lewis was placed on paid administrative leave after his arrest, according to the paper.

Kunik said Coel was told after his arrest that he faces an administrative hearing regarding his employment. He was placed on leave after the shooting.

Punta Gorda agreed in November to pay Knowlton’s family $2 million to settle a lawsuit against the police department, Fox 13 reported.