Police departments around the nation must establish solid working relationships with community leaders before incidents such as the recent death of a 25-year-old man in Baltimore police custody, NYPD commissioners advised in a TV appearance Sunday.

Police chiefs should be telling themselves: "Let me do my outreach now. Let me do more of it, let me do it better," said NYPD Deputy Commissioner for Counterterrorism John Miller on the CBS show "Face the Nation." "Because when the phone rings at 3 o'clock in the morning, if that's the night you're exchanging business cards, you've lost already."

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Miller appeared with NYPD Commissioner William Bratton to comment on a night of chaotic demonstrations by more than a thousand in Baltimore over the death of Freddie Gray, a black man who suffered a spinal cord injury during an April 12 arrest by city police.

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The incident bore many similarities to the July death of Eric Garner, 43, a black Staten Island man who was held around the neck by an NYPD officer trying to subdue him. After a December grand jury decision not to indict Officer Daniel Pantaleo in Garner's death, street demonstrations against police violence broke out.

Later, NYPD unionized ranks used other forms of protest -- most notably, turning their backs against Mayor Bill de Blasio during the funerals of two slain officers. The mayor was seen as sympathetic to protesters and unsupportive of police. The officers' deaths were not directly related to Garner's death.

Bratton said there is less tension in the city now.

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"Public sentiment really came behind the mayor as the event went forward, and I think the raw emotions -- two police officers murdered -- have healed somewhat in the city," he said.