New York Police Department Funeral - January 4, 2015

Police officers line the streets before the funeral of Officer Wenjian Liu in the Brooklyn borough of New York, Jan. 4, 2015.

Police officers from across the country gather for the funeral of New York Police Department Officer Wenjian Liu at Aievoli Funeral Home, in the Brooklyn borough of New York, Jan. 4, 2015,.

Spectators stand at the barricades during the funeral of New York Police Department Officer Wenjian Liu at Aievoli Funeral Home in the Brooklyn borough of New York, Jan. 4, 2015.

Some police officers turn their backs as Mayor Bill de Blasio speaks during the funeral of New York Police Department Officer Wenjian Liu at Aievoli Funeral Home in the Brooklyn borough of New York, Jan. 4, 2015.

Police officers arrive to the funeral of New York Police Department Officer Wenjian Liu at Aievoli Funeral Home, Jan. 4, 2015, in the Brooklyn borough of New York.

Law enforcement officers stand, with some turning their backs, as New York City Mayor Bill de Blasio speaks on a monitor outside the funeral for NYPD officer Wenjian Liu in the Brooklyn borough of New York, Jan. 4, 2015.

From left, New York Police Department Commissioner Bill Bratton, Rikki Klieman, Bratton's wife, New York City Mayor Bill de Blasio, and 1st Deputy Commissioner Benjamin Tucker exit the wake for New York Police Department Officer Wenjian Liu at a funeral h