BOSTON — Massachusetts’ chief medical examiner is still working to figure out exactly what killed the Boston Marathon bombing suspect who unleashed a barrage of gunfire and explosives on police before dying during a gateway attempt.

Terrel Harris of the state Executive Office of Public Safety and Security says the medical examiner hasn’t determined the cause of death of 26-year-old Tamerlan Tsarnaev (tsahr-NEYE’-ehv).

Tsarnaev and his brother, 19-year-old Dzhokhar (JOH’-kahr), are accused of planting two explosives near the marathon finish line Monday, killing three people and injuring more than 180. A motive remains unclear.

The older brother was killed during a getaway attempt early Friday. Police say he was run over by a car driven by his brother as he fled the gunfire. The younger brother was captured Friday night after a gunbattle with police and remains hospitalized in serious condition.

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