Chicago is bracing for massive protests over the prison release of former city police officer Jason Van Dyke, who was convicted of murder in the 2014 line-of-duty shooting of 17-year-old Laquan McDonald.

The 43-year-old Van Dyke was let go from the custody of the Illinois Department of Corrections Thursday morning, sources told ABC Chicago station WLS. His release came after he served half of a six-year, nine-month sentence he was given in 2019.

In anticipation of Van Dyke’s release, Chicago police and city officials met with business leaders on Wednesday for a security briefing and Mayor Lori Lightfoot attempted to allay fears in a statement she issued Thursday morning.

“I understand why this continues to feel like a miscarriage of justice, especially when many Black and brown men get sentenced to so much more prison time for having committed far lesser crimes,” Lightfoot said. “It’s these distortions in the criminal justice system, historically, that have made it so hard to build trust.”

Lightfoot noted that Van Dyke was the first Chicago police officer in more than a half century to be convicted of a crime committed in the line of duty.

“While I know this moment is disappointing, it should not prevent us from seeing the significant progress Van Dyke’s prosecution and conviction represent,” she said.

Demonstrators are expected to gather Thursday afternoon at Federal Plaza in Chicago in hopes of delivering a letter to U.S. Attorney John Lausch requesting federal civil rights charges be brought against Van Dyke.

The Rev. Jesse Jackson and members of his Rainbow PUSH Coalition, are expected to join Black Lives Matter Chicago protesters and Father Michael Pfleger, the Catholic priest and Chicago activist, at Thursday’s protest.

More demonstrations are being planned for Friday, officials said.

On Tuesday, Sens. Dick Durbin and Tammy Duckworth, both Democrats from Illinois, issued a joint letter to U.S. Attorney General Merrick Garland requesting a briefing on a federal investigation into the McDonald murder case. The senators said the U.S. Attorney’s Office for the Northern District of Illinois has refused to say whether the federal investigation launched in April 2015 was still ongoing or closed.

McDonald was killed on Oct. 20, 2014. Police dashcam video of the shooting played at Van Dyke’s trial showed McDonald was armed with a knife but did not appear to be moving toward the police officers following him when Van Dyke responded and opened fire on the teen 16 times in a span of 15 seconds.

Van Dyke testified at his 2018 trial that he believed McDonald was coming at him with a knife. An autopsy showed McDonald had a small amount of the hallucinogenic drug PCP in his system when he died.

The Cook County Circuit Court jury found Van Dyke guilty on charges of second-degree murder and 16 counts of aggravated battery with a firearm, one for each shot he fired at McDonald.

Four Chicago police officers were subsequently fired over their alleged cover-up of McDonald’s killing after an investigation found they made false statements to investigators about the shooting.

Van Dyke was initially sent to a state prison to serve his sentence, but after he was beaten by fellow inmates in his cell he was transferred to a federal prison in 2019.