An anonymous tip from a caller – delivered through the county’s Crime Stoppers hot line – helped catch a suspect in Thursday night’s armed robbery at a Lawrence convenience store.

Undersheriff Kenny Massey, who has answered Crime Stoppers calls for more than three years, said it was the first case he’d seen in which a call to the hot line helped solve a crime in the minutes after it happened.

“Usually they’re well after the fact,” he said.

Marcus J. Bell, 20, 2124 W. 26th St., was charged Friday with aggravated robbery for the holdup Thursday night at Presto Convenience Store, 2330 Iowa. Police said they thought Bell was the lookout man during the robbery.

As of Friday evening, Lawrence Police still were looking for a second “person of interest” – 20-year-old Darnell Thomas of Lawrence – but stopped short of calling him a suspect.

“He’s a person that we’d like to talk to,” police spokeswoman Kim Murphree said.

A clerk said a man with what appeared to be a single-barrel pump shotgun stormed into the store and began to scream and curse. The only customer inside followed orders and dropped to the ground.

With the gun near his face, the clerk emptied the register and placed the cash onto the counter.

The anonymous caller – Massey wouldn’t identify whether it was a male or female – said he or she knew Bell by name and had seen him hanging out in front of the store acting suspicious.

The caller said Bell “was nervous, and moving around – just like he was waiting for something to happen,” Massey said, and said he lived in a nearby apartment complex. Massey verified with dispatchers that there had been an armed robbery and relayed Bell’s name to a police supervisor.

Bell was arrested around 1:30 a.m.

Some callers to the hot line, 843-TIPS, are eligible for a cash reward if their information leads to an arrest.

Massey said he would take the case to the board of the local Crime Stoppers, a private agency, and the board would decide what, if any, reward the person will receive. He gave the caller a code number to use for checking the status of the reward.