Garner's death has led to outrage, especially after video obtained by the New York Daily News appeared to show that the man was put into a chokehold as he was arrested.
The chokehold is prohibited by NYPD departmental policy.
The video shows officers approaching Garner, who initially denies that he's selling loose cigarettes.
"I'm minding my business why don't you leave me alone," Garner can be heard saying.
Eventually when police officers move in, Garner appears to not comply and at least five officers wrestle him to the ground as they attempt to handcuff him.
As Garner is being held down, he can be heard telling police that he "can't breathe." Eventually when officers realize he is not responsive, they called in an ambulance, which took Garner to a hospital where he died a short time later.
The apparent violence of the arrest led to outrage and the internal investigation. On line, numerous people tweeted #JusticeforEricGarner, calling attention to the deadly incident.
ABC News' Dean Schabner contributed to this report.