Buddhist mourners burn fake money during a candlelight vigil for slain New York Police Department (NYPD) officer Wenjian Liu one day ahead of his funeral in Manhattan, New York January 3, 2015. Liu, 32, and his partner Rafael Ramos, 40, were shot to death on December 20, 2014 as they sat in their squad car in Brooklyn. Their killer, Ismaaiyl Brinsley, who killed himself soon after, had said he was seeking to avenge the deaths this summer of two unarmed black men at the hands of white police officers. (Photo by Stephanie Keith/Reuters)

Spectators watch as the funeral procession for Officer Wenjian Liu passes in the Brooklyn borough of New York, Sunday, January 4, 2015. (Photo by Seth Wenig/AP Photo)

Motorcycle police officers ride under a giant American Flag as they lead the procession route during the funeral of New York Police Department Officer Wenjian Liu, Sunday, January 4, 2015, in the Brooklyn borough of New York. Liu and his partner, officer Rafael Ramos, were killed Dec. 20 as they sat in their patrol car on a Brooklyn street. The shooter, Ismaaiyl Brinsley, later killed himself. (Photo by John Minchillo/AP Photo)

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 January 4, 2015. Tens of thousands of law enforcement officers from across the country gathered on Sunday for the funeral of the second of two New York City policemen killed last month in an ambush that galvanized critics of Mayor de Blasio. (Photo by Shannon Stapleton/Reuters)

Onlookers stand to the side as motorcycle riding police officers lead the procession route during the funeral of New York Police Department Officer Wenjian Liu, Sunday, January 4, 2015. (Photo by John Minchillo/AP Photo)

Widow Pei Xia Chen holds a photo of slain New York Police Department officer Wenjian Liu as his casket departs his funeral in the Brooklyn borough of New York January 4, 2015. New York Mayor Bill de Blasio appealed for reconciliation on Sunday in his eulogy for the second of two police officers murdered last month, two deaths that led to accusations the mayor had contributed to an anti-police climate. (Photo by Carlo Allegri/Reuters)

Widow Pei Xia Chen clutches the folded flag of slain New York Police Department officer Wenjian Liu as his casket departs his funeral in the Brooklyn borough of New York January 4, 2015. (Photo by Carlo Allegri/Reuters)

Widow Pei Xia Chen reacts while clutching a photo of slain New York Police Department officer Wenjian Liu as his casket departs his funeral in the Brooklyn borough of New York January 4, 2015. New York Mayor Bill de Blasio appealed for reconciliation on Sunday in his eulogy for the second of two police officers murdered last month, two deaths that led to accusations the mayor had contributed to an anti-police climate. (Photo by Carlo Allegri/Reuters)

The lead funeral procession vehicle for NYPD officer Wenjian Liu makes its way under a US flag en route to the cemetery in the Brooklyn borough of New York January 4, 2015. (Photo by Shannon Stapleton/Reuters)

A child takes photos of slain New York Police Department officer Wenjian Liu's funeral from a window, in the Brooklyn borough of New York January 4, 2015. (Photo by Carlo Allegri/Reuters)

The hearse carrying NYPD officer Wenjian Liu makes its way under a U.S. flag en route to the cemetery in the Brooklyn borough of New York January 4, 2015. (Photo by Shannon Stapleton/Reuters)

A woman puts her hand over her heart as the funeral procession for NYPD officer Wenjian Liu leaves in the Brooklyn borough of New York January 4, 2015. (Photo by Shannon Stapleton/Reuters)

NYPD police helicopters fly over the funeral procession for NYPD officer Wenjian Liu as law enforcement officers salute in the Brooklyn borough of New York January 4, 2015. (Photo by Shannon Stapleton/Reuters)

A woman salutes as another wipes tears from her eyes along the funeral procession route for NYPD officer Wenjian Liu in the Brooklyn borough of New York January 4, 2015. (Photo by Shannon Stapleton/Reuters)

A limo for family members is seen following the funeral of slain New York Police Department officer Wenjian Liu's in the Brooklyn borough of New York January 4, 2015. (Photo by Carlo Allegri/Reuters)

A hearse carrying the casket containing New York Police Department officer Wenjian Liu makes its way in a procession down 65th Street following his funeral service in the Brooklyn borough of New York January 4, 2015. (Photo by Mike Segar/Reuters)

New York City police turn away from a screen showing New York Mayor Bill de Blasio speaking during the funeral service for New York Police Department officer Wenjian Liu in the Brooklyn borough of New York January 4, 2015. (Photo by Mike Segar/Reuters)

New York City police line the streets for the funeral service of New York Police Department officer Wenjian Liu in the Brooklyn borough of New York January 4, 2015. (Photo by Mike Segar/Reuters)

Mourners cram together on the sidewalk to listen to the funeral service for New York Police Department officer Wenjian Liu in the Brooklyn borough of New York January 4, 2015. (Photo by Mike Segar/Reuters)

A flower car leads the hearse carrying the casket of New York Police Department officer Wenjian Liu in a procession down 65th Street following his funeral service in the Brooklyn borough of New York January 4, 2015. (Photo by Mike Segar/Reuters)

A woman wipes away tears as she and other mourners cram on the sidewalk to listen to the funeral service for New York Police Department officer Wenjian Liu in the Brooklyn borough of New York January 4, 2015. (Photo by Mike Segar/Reuters)

Police stand in silence on the street as they listen to the funeral service for New York Police Department officer Wenjian Liu in the Brooklyn borough of New York January 4, 2015. (Photo by Mike Segar/Reuters)

Police stand in formation down 65th street as they listen to the funeral service for New York Police Department officer Wenjian Liu in the Brooklyn borough of New York January 4, 2015. (Photo by Mike Segar/Reuters)

Police officers from the 84th Precinct listen during the funeral for slain New York Police Department officer Wenjian Liu in the Brooklyn borough of New York January 4, 2015. (Photo by Carlo Allegri/Reuters)

A police officer departs from the funeral for slain New York Police Department officer Wenjian Liu in the Brooklyn borough of New York January 4, 2015. (Photo by Carlo Allegri/Reuters)