CHICAGO (AP) — Protest groups returned to the streets of Chicago on Wednesday, one day after the city released a squad-car video showing a white police officer fatally shoot a black teenager.

Prosecutors on Tuesday charged Officer Jason Van Dyke with first-degree murder for the 2014 death of 17-year-old Laquan McDonald, who was shot 16 times.

Several hundred demonstrators marched in and near downtown and outside a Chicago police building on Tuesday night, chanting and at times blocking intersections, but police reported few problems. A protest was held Wednesday afternoon at City Hall and others were planned at various locations Wednesday night and in a downtown shopping area on Friday.

Here's a look at what's happened so far and what's expected next:

THE SHOOTING

On the night of Oct. 20, 2014, police responded to a call of a teen with a knife. Witnesses said he was breaking into cars and stealing radios.

Police have said McDonald refused their orders to drop the knife and walked away from them. The police union also said that at one point McDonald lunged at officers with the knife.

The video released Tuesday shows McDonald jogging down an empty lane on a four-lane street and then veering away from Van Dyke and another officer who emerge from a police SUV drawing their guns. Within seconds, Van Dyke begins firing. McDonald spins around and falls to the pavement as Van Dyke keeps shooting.

Cook County State's Attorney Anita Alvarez said Van Dyke emptied his weapon before his partner stepped forward and kicked the knife away from McDonald.

Alvarez said police later recovered a knife with a 3-inch blade that was folded into the handle.

An autopsy report showed McDonald had the hallucinogenic drug PCP in his system.

___

THE VIDEO RELEASE

A freelance journalist filed a Freedom of Information Act request for the video after learning of the shooting, but the Chicago Police Department refused to release it, saying it could hurt investigations.

Activists and attorneys argued the public had a right to see the video, and last week a Cook County judge agreed. He gave the city until Wednesday to make it public.

At a joint news conference Tuesday evening, Chicago Mayor Rahm Emanuel and Police Superintendent Garry McCarthy worked to discourage the kind of unrest seen in cities such as Baltimore and Ferguson, Missouri, after young black men were slain by police or died in police custody.

Emanuel and McCarthy described the shooting of McDonald as an unusual and tragic incident and called on the public to protest peacefully, with the mayor noting that McDonald's family had asked people not to resort to violence in the teen's name.

___

THE INVESTIGATION

Alvarez said Tuesday she decided to announce the charges against Van Dyke earlier than planned because of the video's release. But she said the video becoming public wasn't a factor in her decision to charge him with first-degree murder.

She said it was clear McDonald didn't pose a threat to the officer and that his use of force was improper.

Alvarez also defended the length of time it took to file charges. She said her office has been working with the FBI and the U.S. Attorney's Office since mid-November on an active, joint criminal investigation and that police-involved shootings are "highly complex" cases that take longer than typical shootings to investigate.

___

THE OFFICER

Van Dyke turned himself in to authorities Tuesday, and a judge ordered him held without bond.

Van Dyke, 37, has been a Chicago police officer since 2001. He is married and has two children.

His attorney, Dan Herbert, said the officer has never been disciplined. He said Van Dyke feared for his life when he fired at McDonald and that the case should be tried in the courtroom, not in social media or on city streets.

McCarthy said the officer, who had been on desk duty while the shooting was investigated, is no longer being paid. Another bond hearing is scheduled for Monday.

___

PROTESTS

Chicago police said five people were arrested during protests Tuesday night and early Wednesday, including a 22-year-old Chicago man charged with a felony count of aggravated battery of a police officer.

A judge dismissed the charge Wednesday afternoon after the state's attorney's office recommended it be dropped. Prosecutors did not say why their office made the recommendation.

A 38-year-old man from Murrieta, California, was charged with felony possession of a controlled substance and misdemeanors for carrying a stun gun and a knife.