Ahead of slain police officer Wenjian Liu's funeral tomorrow, Police Commissioner Bill Bratton told all officers to refrain from turning their back to Mayor Bill de Blasio. Bratton stated in the department-wide memo, "A hero’s funeral is about grieving, not grievance."

The memo, which the Post's sources call an attempt to "shame [cops] into good behavior", continues: "I issue no mandates and I make no threats of discipline. But I remind you that when you don the uniform of this department, you are bound by the tradition, honor, and decency that go with it."

Liu and Officer Rafael Ramos were killed on December 20th while in their squad car, parked on Tompkins Avenue near Myrtle in Bedford-Stuyvesant. They were fatally shot—executed, as Police Commissioner Bill Bratton said—by Ismaaiyl Brinsley, 28, who later killed himself in a subway station. Brinsley posted on social media that he wanted to get back at police for killing Eric Garner in Staten Island and Michael Brown in Ferguson, Missouri, but Brinsley's family also said he was mentally ill and "spiraling." Earlier that day Brinsley had shot and wounded an ex-girlfriend in Baltimore.

The police officers' union seized on the horrible line-of-duty killings to blast de Blasio for not supporting cops, whether through the mayor's support of protesters to rally against police brutality or by the mayor revealing he told his son Dante, who is half-black, to be careful with the police. The head of the Patrolmen's Benevolent Association said de Blasio had Liu's and Ramos' "blood on his hands".

At Ramos' funeral last week, officers from the NYPD and other outside departments turned their backs to de Blasio during his eulogy for Ramos (the eulogy was broadcast on a screen outside the church). Bratton, who had to discuss (and discredit) the action on morning talk shows, said the action effectively hijacked the funeral from Ramos' family, "The country’s consciousness of that funeral has focused on an act of disrespect shown by a fraction of those…officers. All officers were painted by it, and it stole the valor, honor, and attention that rightfully belonged to the memory of detective Rafael Ramos’s life and service. That was not the intent, I know. But it was the result."

Turned backs for Mayor de Blasio at Police Officer Rafael Ramos' funeral (AP)

One cop fumed to the Post, "Obviously he’s doing this to help his boss, de Blasio. He’s taking his side. He’s trying to protect him and not make him look bad." However, Bratton has been vocal in denouncing protesters as being part of "anti-societal initiatives," which does fly against de Blasio's more progressive views. Another officer explained, "I did that because I feel Mayor de Blasio does not like cops, and I would never do anything to disrespect another cop or his family... [Bratton] cares about his boss more than the 35,000 cops he’s in charge of,"

The NY Times reports, "In a statement on Friday, Michael Palladino, the president of the Detectives’ Endowment Association, said his organization would not instruct its members on how to behave at Officer Liu’s funeral. 'But detectives have feelings too, and I respect their decision to express them if they so choose.'"

Ed Mullins, of the Sergeants' Benevolent Association, spoke to the Post, "If you’re the mayor and you have to direct the commissioner to respect you, it’s a total embarrassment for the office. Are they going to order cops to go have dinner with him next?... I remind my members of their first amendment rights of expression. It’s your choice. Choose what makes sense to you."

But the presidents of the Captains' Endowment Association, Roy Richter, told his members, "In this forum the appropriate protest is not a sign or turning away from mourners, or people the family has asked to speak, but rather cold, steely silence... In the coming days and weeks you will be looked upon by many for guidance, leadership and advice at a time when many of our peers and officers under our care are deeply angry. Unfortunately, but understandably, this anger provided visual displays of back-turning at the funeral of Police Officer Ramos that caused pain for his loved ones."

A wake for Liu is being held today at Ralph Aievoli & Son Funeral Home in Dyker Heights Saturday. His funeral will be tomorrow, also at Ralph Aievoli & Son Funeral Home, followed by a burial at the Cypress Hills Cemetery.