The killings of two unarmed black men by white police officers in Missouri and New York this summer touched off protests and a national debate over police conduct that intensified after grand juries declined to indict the officers.
Tensions escalated further after two New York City police officers were killed last weekend by a man who suggested in online posts that their slayings were in retaliation for the deaths of Michael Brown in Ferguson, Missouri, and Eric Garner in New York City. The gunman committed suicide.
Some key developments in the aftermath:
NYPD RECRUIT GRADUATION
Mayor Bill de Blasio, whose relationship with the New York Police Department has been particularly tense in recent weeks, was booed and heckled by some in the crowd when he addressed police recruits at a graduation ceremony Monday.
The event came two days after hundreds of police officers turned their backs to a video monitor outside a Queens church showing de Blasio speak at Officer Rafael Ramos' funeral.
The cadets sat at attention Monday when de Blasio spoke but boos and heckles could be heard from some in the crowd where the graduates' friends and families sat. About a dozen people in the crowd stood and turned their backs, but most applauded politely when he finished speaking.
Police unions have criticized de Blasio as too sympathetic to police critics who protested over the Garner and Brown cases.
THREATS TO OFFICERS
A man fired a rifle at two Los Angeles officers in a patrol car Sunday night, but no one was injured.
One man is under arrest and a second suspect was still being sought Monday evening in the shooting in South Los Angeles, a police spokeswoman said.
The two officers were responding to a radio call and driving slowly in the neighborhood around 9:30 p.m. when they saw the muzzle flash of a rifle pointed in their direction, Officer Nuria Venegas said. The officers returned fire, but no one was hit.
In southwestern Pennsylvania, a man has been jailed on charges he posted Facebook comments encouraging people to kill police the same day a man fatally shot two New York City officers.
Steven Drake Jr., 29, was arrested Wednesday in McDonald. Police there were alerted to the Dec. 20 posts by officers in a nearby community. Among the comments Drake allegedly posted were: "The police brought this on themselves! I say kill them all! Enough is enough." The posts also referenced the killings of Brown in Missouri and Garner in New York.
In Fort Worth, Texas, a 17-year-old was arrested after he posted a photo of himself pointing a gun at a police car on Twitter with the caption: "Should I do it? They don't care for a black male anyways."
Police determined the gun was an Airsoft replica but said they still considered the photo a threat.
FUNERAL SET FOR SECOND NYPD OFFICER
Viewing and visitation for Wenjian Liu, who was killed along with Ramos, will be held Saturday, with a funeral Sunday morning. The funeral arrangements for Liu took some time because of relatives who had to travel from China.
Liu, 32, was a valuable asset to the NYPD because he was conversant in several Chinese dialects and helped the department with community relations in heavily Chinese neighborhoods, said James Ng, president of the National Asian Peace Officers Association.
CHARITY FOR OFFICERS' FAMILIES
Efforts to support the families of Ramos and Liu have raised $120,000, de Blasio said Monday. The Mayor's Fund to Advance New York City has raised the money in pledges through the Fallen Heroes Relief Effort, he said.
In addition, a charity created after the Sept. 11 terrorist attacks says it has so far raised $250,000, or about a third of what it needs, to pay off the home mortgages for the families of Ramos and Liu.
The Stephen Siller Tunnel to Towers Foundation said Sunday that contributions poured in from as far away as Hawaii, Italy and the United Kingdom.
DEMONSTRATIONS AROUND THE COUNTRY
Residents rallied over the weekend in Goshen, Indiana, to show their support for law enforcement. Gathering at the Elkhart County Courthouse on Saturday, hundreds carried signs reading "Support Our Police Officers" and "Standing With The Thin Blue Line."
Senior police chaplain Jim Bontrager told the crowd that officers "see the worst of humanity over and over" but they rarely get a thank-you from the public or the police brass.
A candlelight vigil was held Sunday evening for an Arizona police officer who was killed while responding to a domestic violence call over the weekend. Flagstaff Officer Tyler J. Stewart, 24, died Saturday after being shot multiple times.
And in Boston, activists are planning to protest recent killings by police at the city's New Year's Eve celebration.
The group "First Night Against Police Violence" plans to hold a "die-in" at 5 p.m. Organizers hope at least 100 people will participate in the demonstration, in which activists lie down in the street pretending to be dead.
FERGUSON POLICE SPOKESMAN SUSPENDED
The Ferguson Police Department suspended a spokesman after he referred to a Brown memorial as "a pile of trash."
A statement the city provided to The Associated Press on Sunday didn't identify the officer who made the remark to a newspaper. The memorial at the site of Brown's death was damaged last week after a car apparently hit it.
The city says the spokesman denied making the comment to his supervisors but later admitted that he'd misled his bosses.
City officials said negative remarks about the memorial "do not reflect the feelings of the Ferguson Police Department."