New York Police Officer Wenjian Liu, 32, is seen in an undated picture provided by the New York Police Department December 20, 2014. A gunman ambushed and fatally shot two New York City police officers on Saturday and then killed himself, police said, and a social media post indicated it may have been in revenge for the police chokehold death of an unarmed black man. Bratton identified the slain officers as Rafael Ramos, 40, and Wenjian Liu, 32. Liu had been married for two months. [Photo/Agencies]