Police are asking for the public’s help to find a serial armed robber who has hit more than 20 metro-area discount stores since February.

This discount bandit has held up 13 Family Dollar and Dollar General stores in DeKalb County, as well as 12 other stores in Gwinnett and Henry counties and the cities of Lilburn, Atlanta and Lithonia, DeKalb County Police Chief Cedric Alexander said Wednesday afternoon.

“We just learned he hit another Family Dollar store in Henry County about an hour ago,” Alexander told reporters during a 3 p.m. news conference. “He is extremely dangerous. We need to get this guy off the streets yesterday.”

Police said the suspect enters each store at random times after casing the location and brandishes a weapon, regardless of whether customers are present or not. He demands cash from the registers and quickly flees the scene, authorities said, often escaping in a silver Cadillac SUV investigators believe is parked at an adjacent location.

“He operates very quietly and knows how to mark a target,” Alexander said. “He’s in there for a very brief time.”

No one has been hurt, he said, but police don’t want to take a chance that the robber might harm someone during a robbery.

“With the consistency of the robberies and the fact that there have been customers present, we are considering him very, very dangerous,” Alexander said.

Police described the suspect as a black man in his early to mid-20s who is 5-foot-6 to 5-8 and about 150 pounds. They said he has never robbed the same store twice.

The bandit’s first caper was Feb. 18 at the Family Dollar at 3855 Lawrenceville Highway near Tucker, police said.

Police began to tie the robberies together after a few weeks, Alexander said.

After the first four DeKalb robberies, all in February, the bandit seemed to go dormant in the county, according to police records.

Three months later, DeKalb police caught a break.

On May 1, surveillance video captured a man fitting the same description as the suspect in the February robberies holding up the Family Dollar at 3590 Panola Road near Lithonia.

Police released the footage and were contacted by other agencies.

Investigators believe the man struck four times in Gwinnett County, twice in Lilburn, once in the City of Lithonia, two times inside Atlanta police jurisdiction, and as many as three times in Henry County, including Wednesday’s robbery.

The FBI has been called in to help with what has become a joint investigation, Alexander said.

“We need support from the community,” he said. “Somebody knows this person. If you have information about him, please let us know.”

Anyone with information on any of these robberies is asked to call Crime Stoppers at 404-577-8477. Anonymous calls are accepted and a reward is available for information leading to an arrest or prosecution.