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On Dec. 20, Marcus Butler was cruising along Georgia Avenue in his blue Cadillac with tinted windows when he was stopped for a fairly routine violation: expired plates. When officers discovered he didn’t have a valid driver’s license, Butler, 21, was arrested. But the more startling finding was yet to come.

Upon searching the car, officers recovered an AK-47 and a magazine loaded with 18 rounds in his back seat. This assault rife has a notorious rep. In Russia, it’s celebrated as the weapon that solidified the Soviet Empire’s mid-century military might. Stateside, it was the gun used in the recent Nebraska mall murder rampage. But, here in the District—gun ban and all—it’s a rare find.

“You don’t find them often, like the 9 mm,” says Third District Commander Larry McCoy. “I’d be surprised if we got more than four in my district this year.”

Butler is no longer in police custody, but his AK-47 is.

“We’ll run a ballistic check. If any shell casings in other scenes come back to that gun than obviously, [investigators will] be taking a hard look at him,” says McCoy.