>> reporter: look closely, one officer, daniel pantaleo, who is white, has his arm around gardner's neck. listen to gardner's cries muffled by the pavement. >> i can't breathe. i can't breathe. >> reporter: what police may not have known was that gardner suffered from asthma. his body appears to go limp. gardner was later declared dead at a nearby hospital. police say he had a heart attack and died on the way. less than a month after his death, the new york city medical examiner made the official ruling. the cause of death, compression of neck, a chokehold. plus compression of chest and prone positioning during physical restraint by police. his death was ruled a homicide. complicating matters -- the m.e. also found that asthma, obesity and cardiovascular disease were contributing factors. the city erupted in protests. >> we actually came out here to give support and make sure that we show the family of eric