NEW YORK (CBSNewYork) -- The NYPD is asking for the public's help in ending a frightening series of robberies within Manhattan's subway system.
Since May, two men have been targeting straphangers on the No. 3 and C subway trains, demanding their valuables and threatening to shoot them, police said.
In all but one case, the robbers took their victims' iPhones, police said.
Police caught the suspect's alleged accomplice, 23-year-old Bruce Williams, on July 3, a day after a man was robbed at gunpoint at the 145 Street and Lenox Avenue station.
Williams has been charged with robbery and criminal possession of stolen property in connection with an incident on a C train on June 30.
Police said in that case, a woman was robbed of her iPhone and cash before the suspects got off the train at the 72nd Street and Central Park West station.
The outstanding suspect is described as a black man in his early 20s. He is believed to be about 6-foot-1 with a slender build and brown eyes.
He was last seen wearing a grey hooded sweater, blue jeans and a Yankees baseball hat, police said.
Anyone with information is asked to call Crime Stoppers at 1-800-577-TIPS (8477).
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