Walgreen's is one of more than 40 pharmacies that a robber is using as his own personal drug supply. His favorite pharmacies to rob appear to be Walgreen's and CVS.

"He prefers CVS and Walgreens because they're laid out basically the same so he knows exactly where he's going each time," says Detective Dale Wilson.

Wilson's part of a team of law enforcement officers, typically dedicated to solving bank robberies, who are on the trail of the oxycontin thief. The Bank Robbery Task Force works with the FBI and has federal authority to go after criminals. They've set their sites on the oxycontin thief.

Officers say he walks into the front door of a pharmacy, walks back to the drug counter, brandishes a gun, demands oxycontin then walks away with quite a haul. Police say the robber always has a getaway car waiting.

The drug oxycontin is a strong painkiller, available by prescription. But illegal users will often grind up the pills and snort the powder, or inject it with a hypodermic needle.

It's an addiction that's could put pharmacy customers in harm's way.

"We feel if he's not apprehended soon there's always the possibility of him getting violent and someone could get hurt," says Wilson.