Wenjian Liu, 32, the second NYPD officer shot and killed in a Dec. 20 ambush, is being laid to rest Sunday in Brooklyn.
"All of our city is heartbroken today," said New York City Mayor Bill de Blasio.
Some police officers turned their backs on de Blasio as he gave a eulogy for Liu, The New York Times reports. The same act occurred at Ramos’ funeral on Dec. 27. Liu's funeral was delayed so family could arrive from China.
New York City Police Commissioner William Bratton had asked officers to refrain from protesting at Liu’s funeral, which combined Buddhist and NYPD mourning rituals.
"A solemn day as we lay to rest NYPD Detective Liu, one of the finest. We will never forget his sacrifice," Bratton said on Twitter.
Liu and Rafael Ramos, 40, were shot by Ismaaiyl Brinsley while they were sitting in a patrol car in Brooklyn. Brinsley, 28, referenced the deaths of Michael Brown and Eric Garner on social media before the attack.
Brinsley, who also shot his girlfriend in Maryland, then killed himself.
The deaths of Liu and Ramos further inflamed relations between the police, the mayor and New York City residents.
Liu and Ramos have been posthumously promoted to detective. Both funerals were attended by police officers from around the country.
Gavin Stern is a national digital producer for the Scripps National Desk.