The robberies began Nov. 8 in Adams Morgan, when a man in a puffy jacket walked past a grocery store and looked in the window. Then, police said, he came back and went into the store in the 2200 block of 18th Street NW.
He drew a gun and demanded money and four packs of cigarettes. The shopkeeper complied and the man fled, police said.
Three more robberies followed, all of those involving Subway sandwich shops. The most recent was Saturday, at the Subway in the 1900 block of New Hampshire Ave NW.
The others were Thursday in the 800 block of H Street NW near the Verizon Center and Nov. 12 in the 1500 block of North Capitol Street NW.
In each incident, police said, the robber drew a gun, demanded money and fled with the cash.
Police said Alonzo Johnson, 41, of no fixed address, was arrested Monday and charged with armed robbery in all four holdups.