Arnoldo Lemus, 20, left his bookbag on the platform of the Copley Square Station in Back Bay early Sunday morning, Aug. 28, after he boarded a trolley, transit police said. Officers looked inside and found a 9mm pistol with a laser sight and high-capacity magazine.
Lemus returned to the station later that day and "frantically" looked for his bookbag, transit police said. Police arrested him after he approached station staff about retrieving it.
Officials charged Lemus with unlawful possession high-capacity feeding device and unlawful possession of ammunition, transit police said.
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