Tens of thousands of police officers were expected along with politicians and other mourners Sunday at the funeral of a New York City policeman killed last month in an ambush that deepened a rift between Mayor Bill de Blasio and the force.

Wenjian Liu, 32, and his partner, Rafael Ramos, 40, were murdered on Dec. 20 as they sat in their squad car in Brooklyn after killer Ismaaiyl Brinsley had stated he was seeking vengeance for the deaths this summer of two unarmed black men at the hands of white police officers.

Brinsley killed himself after ambushing the officers.