NYPD Cops Again Turn Backs on Mayor at Second Slain Officer's Funeral

— -- Thousands of uniformed police officers turned their backs to New York City Mayor Bill de Blasio today as he spoke during a funeral for officer Wenjian Liu despite a warning from their boss.

NYC Police Commissioner Bill Bratton earlier in the week sent a warning to officers who planned to attend the funeral, saying it was "about grieving, not grievance," after several officers turned their backs to de Blasio as he spoke at another officer's funeral last weekend.

"A hero's funeral is about grieving, not grievance," Bratton wrote in a memo sent to officers. The gesture "stole the valor, honor, and attention that rightfully belonged to the memory of Detective Rafael Ramos's life and sacrifice."

The shooting deaths of Liu and Ramos came amid heightened tensions between the police and the mayor over what some police saw as a lack of support for the force.