A tech-savvy police officer from the 84th Precinct helped catch a thief this afternoon. According to cops, a 32-year-old woman fell prey to an armed robber at the High Street station just before 1:20 P.M. The suspect fled with the victim’s pocketbook and iPhone. The victim quickly found an officer stationed on Pearl Street and reported the incident. Officer Benito Ocasio, honored as a Cop of the Month in 2009, suggested that he might be able to track the phone using the victim’s iTunes account. In doing so, they saw that the phone was then in the vicinity of 111 Bridge St. in the Farragut Houses. Responding there, police found the suspect exiting the building…with a ringing phone. He was stopped, positively identified by the victim, and taken into custody. The victim’s property, including credit cards and state ID, was recovered. Police have identified the suspect as Brian Mack, 55. He now faces charges of robbery, grand larceny, menacing, possession of a weapon, and criminal trespass.