A now-former corrections officer finds himself on the other side of the law.

James William Mock III, 28, was fired after police say he sold oxycodone pills to an undercover agent outside a downtown Burger King.

"Mock sold 80, 30-milligram oxycodone pills to the undercover agent," Undersheriff Dwain Senterfitt told a news conference.

He says Mock sold the pills for $1600.

"He was in uniform at the time," he says.

"Somebody gave information to NCIS that we had a corrections officer who was buying pills.  NCIS contacted out department, and they were connected then with our Integrity Unit, and they began a joint investigation about two weeks ago."

Mock joined the Jacksonville Sheriff's Office last April and became a probationary corrections officer last November.

He's charged with selling a schedule one or two synthetic narcotic within 1,000 feet of a convenience business, which is a first-degree felony.

He's also facing a third-degree felony charge for possession of a controlled substance.

"He had additional pills other than the ones he sold," says Senterfitt.