Mourners take part in a candlelight vigil for slain New York Police Department (NYPD) officer Wenjian Liu, a 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/Agencies]