An armed robbery left a 52-year-old man dead in Arlington County on Friday, marking the county’s second homicide in days after more than two years without one.

Police did not release the identity of the victim, reporting only his age and that he lived in Herndon. They said he was killed during a robbery at a jewelry store in the 3200 block of Columbia Pike.

Officer Dustin Sternbeck, a police spokesman, declined to say how the man died or whether a confrontation occurred between the suspect and the victim, citing an ongoing investigation. The suspect is still at large, police said.

Police released surveillance images of the suspect, whom they described as a 5-foot-7 black male with a medium build who wore a neon traffic vest. Police have not decided whether to release additional footage to the public, Sternbeck said.

Sternbeck said that the suspect was inside the jewelry store for less than 20 minutes and that he took jewelry.

Authorities discovered the victim’s body after his family called when he failed to come home Friday.

Sternbeck said the fire department broke its way into the locked jewelry store.

Three days earlier, an apparent murder-suicide near Arlington’s Fairlington neighborhood left a married couple dead. After more than two years without a homicide, two have occurred within days in the county.

“It’s extremely unusual for a jurisdiction of our size and demographic makeup on the edge of a major metropolitan city,” Sternbeck said. “Obviously, we’re concerned.”

Before last week, the previous homicide in Arlington was in March 2010, when county resident Cain Guevara-Estrada, 20, was fatally stabbed in the Lyon Park neighborhood.