Chattanooga police distributed this image from a security camera of a woman who is suspected of robbing two Walgreen's pharmacies of drugs.

To curtail prescription drug robberies at pharmacies, a national drug store chain is installing time-delayed locks on safes containing select medications such as oxycontin in the Chattanooga market.

"We installed these in Knoxville in February," said Robert Elfinger, spokesman for Walgreen Co., a Deerfield, Ill.-based drugstore chain with about 250 stores in Tennessee. "The six months before we installed them, we had more than a dozen robberies. Since then, we've had one pharmacy robbery."

Elfinger said the locks will deter robbers and make employees and customers feel safer.

The time-delayed locks have been used in other markets where pharmacies were getting hit hard, including stores in Washington, Oregon and Idaho, he said.

"In every market we have installed them, we've seen a drastic decline in robberies," Elfinger said. "No. 1, it's a deterrent, and No. 2, it eliminates the availability of the controlled substance. It takes several minutes to open the safe. It's long enough for police to respond and allows more time to be caught on the video surveillance system."

The installation of the delayed locks comes after a lawsuit by a pharmacist at a Walgreens who was fired in Michigan when he fired his handgun to run off bandits who were trying to rob the store's pharmacy.

Jeremy Hoven, 36, filed a lawsuit in federal court after he was fired in May, claiming wrongful termination. His case is pending.

"Store employees receive comprehensive training on how to react to and respond to a potential robbery situation," Elfinger said in an email statement. "Law enforcement strongly advises against confrontation of crime suspects and, in past incidents, employee feedback shows they've found these training procedures to be safe and effective."

In the Chattanooga market, there have been 10 robberies in the past four months at Walgreens stores, according to the company.

"With the increase in robberies, businesses have to do their part," said Lt. Van Hinton with the Hamilton County Sheriff's Office narcotics unit. "It's just not enough to have visual aids like warning signs ... Now pharmacies have to do their part by securing these items for the safety of their customers and the safety of their employees."

The Associated Press contributed to this story.

Contact staff writer Beth Burger at bburger@timesfree press.com or 423-757-6406.