A Chicago officer will not be charged over the fatal shooting of a black man in the city in 2014, prosecutors announced Monday, as they released video footage that appeared to show the suspect armed but running from police during the incident.

Cook County State's Attorney Anita Alvarez said Ronald Johnson III “ignored” commands to stop and drop his weapon and added that the 25-year-old had pointed his gun at officers prior to being shot dead by officer George Hernandez. At a press briefing Monday, Alvarez also released dashcam footage of the shooting — a move long demanded by family members of Johnson.

In the footage, the suspect is seen running across a street with several officers in pursuit. Johnson runs off screen by the time he is struck and killed by two bullets. A slowed-down version of the video shows what appears to be a gun in his hand. A lawyer for the Johnson family said the investigation into the shooting was a "joke" and an affront to the man's family and Cook County citizens.

The decision not to charge Hernandez over the incident comes less than two weeks after another officer did face charges in connection with a separate shooting — which was also captured by squad car dashcams.

Last month, Alvarez charged Jason Van Dyke with first-degree murder in the death of 17-year-old Laquan McDonald, who was shot 16 times.

Monday’s announcement regarding the Johnson case comes on the same day that the Justice Department announced it had opened a wide-ranging investigation into the patterns and practices of the Chicago Police Department.

U.S. Attorney General Loretta Lynch said the civil rights probe will examine if the city’s police violated the Constitution or federal law and will focus on concern over the use of deadly force and racial bias.

After showing the Johnson shooting video, Alvarez said she had “pretty much opened the door” on the footage.

“We're in different times right now when we're talking about transparency and what the public wants to see,” she added.

When asked why there was no audio on this video and others, Alvarez said: “That's a problem for the Chicago police department and I think they need to answer to that. … ime and time again we look at these videos and there is not any audio.”

Alvarez has been criticized for not filing charges earlier in the McDonald case, in which the video shows the teen veering away from officers on a four-lane street when Van Dyke, seconds after exiting his squad car, opens fire from close range. The officer continues shooting after McDonald crumples to the ground and is seen barely moving.

The Chicago City Council signed off on a $5 million settlement with McDonald's family even before the family filed a lawsuit, and city officials fought in court for months to keep the video from being released publicly.

The city's early efforts to suppress its release coincided with Mayor Rahm Emanuel's re-election campaign, when the mayor was seeking African-American votes in a tight race.

Since the release of the McDonald video, Emanuel forced Police Superintendent Garry McCarthy to resign and formed a task force to examine the police department. But the calls for the mayor to resign — something he said he will not do — have grown louder from protesters, including the voices of more than 200 people during a march Sunday.

Politicians, including Democratic presidential candidate Hillary Clinton and Illinois Attorney General Lisa Madigan, called for the federal civil rights investigation. Veteran civil rights activist, the Rev. Jesse Jackson, said he hopes it would focus not only on the police department, but on Emanuel's office and the Cook County State's Attorney's office, which he and others have criticized for taking so long to bring charges against Van Dyke.

“All three of them — the police, City Hall and the prosecutor's office — are suspect,” Jackson said. “We cannot trust them.”

The Justice Department has opened 23 investigations of police departments since the start of the Obama administration.

If the Justice Department finds systemic violations, the investigations typically result in court-enforceable agreements between the federal government and the community that serve as blueprints for change and are overseen by an independent monitor. The federal government has the option of suing a police department that is unwilling to make changes.

Meanwhile, Illinois lawmakers are separately pushing forward legislation to make it easier for videos depicting shootings by police to be publicly released.

The legislation, introduced by Chicago Democrat Rep. Arthur Turner, would require police agencies that want to deny release of a video under the Freedom of Information Act to prove their case in court.

The Chicago Tribune reported that Turner's legislation has support from co-sponsor Rep. David McSweeney, a Republican from Barrington Hills. The two met last month when Chicago police released the video of the police shooting of McDonald.

Al Jazeera and wire services