Democratic presidential candidate New York City Mayor Bill de Blasio speaks during the Democratic presidential debate in Detroit.
Washington CNN  — 

New York Mayor Bill de Blasio was asked on the Democratic presidential debate stage on Wednesday to answer for his handling of New York police officer Daniel Pantaleo.

Pantaleo is accused in a July 2014 confrontation of fatally choking Eric Garner, whose words – “I can’t breathe” – became a rallying cry in the Black Lives Matter movement. The Justice Department decided earlier in July to not pursue charges against Pantaleo.

Former Secretary of Housing and Urban Development Julián Castro called Wednesday for Pantaleo’s immediate removal from duty.

“Officer Pantaleo used a chokehold that was prohibited by NYPD. He did that for seven seconds. Eleven different times Eric Garner said he couldn’t breathe. He knew what he was doing, that he was killing Eric Garner, and yet he has not been brought to justice. That police officer should be off the street,” Castro said.

Asked by CNN’s Jake Tapper why Pantaleo is still on the police force, de Blasio said Garner’s family is “going to get justice.” He said New York is “changing fundamentally how we police” and “there will never be another tragedy. There will never be another Eric Garner.” De Blasio did not specify how Garner’s family will receive that justice.

New York Sen. Kirsten Gillibrand said the mayor’s response wasn’t enough. Pantaleo, she said, “should be fired now,” adding that if she were mayor she would dismiss him. And if she were president, Gillibrand said, she would have a “full investigation” into Garner’s death with a publicly released report.

That call had been echoed by protesters earlier in the CNN presidential debate, who interrupted de Blasio chanting, “Fire Pantaleo.”

While the candidates remained onstage, de Blasio’s Twitter account posted: “To the protestors in the audience today: I heard you. I saw you. I thank you. This is what democracy looks like and no one said it was pretty.” A post from New Jersey Sen. Cory Booker’s Twitter account supported the protesters, saying, “To the folks who were standing up to Mayor de Blasio a few minutes ago—good for you.”