Durham, N.C. — Stephen Lavance Oates, 19, charged in a Duke University graduate student’s death, was indicted Wednesday in a series of armed robberies.

Oates is under indictment in the death of Abhijit Mahato, 29, who was found shot to death inside his apartment on Jan. 19.

Prosecutors believe Oates robbed Mahato at gunpoint and stole $200, a wallet and cell phone from him. They believe that Oates held up three other people at gunpoint that same day.

Oates and William Dozia Smith, 20, of Anthony Street, were indicted Wednesday for the role police charge they played in a series of robberies going back to November. Many of the victims were Hispanic. They shot one robbery victim and injured another, police alleged.