Police are looking for the suspect who followed a 69-year-old man into the elevator of a Bronx building and punched and kicked him before stealing the chain around his neck and running off.
Authorities say the elevator assault happened at about 7 p.m. Wednesday.
The suspect is described as a being about 5 feet 4 inches tall and in his 20s with a thin build and short black hair.
Police released surveillance video of the assault.
Anyone with information about the incident is asked to call Crime Stoppers at 1-800-577-TIPS (8477). Texts can also be submitted online.