Lamin Sillah was shot to death just minutes before ending his shift at the station at East 128th Street and Southern Boulevard.
The 21-year-old suspect was taken into custody when he showed up for a meeting with his parole officer.
Police are still looking for another suspect.
The 28-year-old Sillah was in the office when two suspects rode up on bicycles to RC Petroleum. Sillah's family said he had only started working at the gas station 10 days prior to the shooting, and that the came to U.S. with a student Visa from Gambia just 10 months ago to get more education.
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