Bolcer says his death was caused by "the compression of his chest and prone positioning during physical restraint by police." She says asthma and heart disease were contributing factors.
Garner, who is black, was being arrested for selling untaxed, loose cigarettes. Video shows him being placed in a chokehold by a white officer. The video has caused widespread outcry, and Attorney General Eric Holder has said the Justice Department is "closely monitoring" the investigation into his death.
The NYPD hasn't responded to a request for comment on the medical examiner's ruling.