CHICAGO (CBS) — A Cook County judge has appointed Kane County State’s Attorney Joseph McMahon to take over the prosecution of Chicago Police Officer Jason Van Dyke, who is charged with murder in the 2014 death of Laquan McDonald.

Judge Vincent Gaughan agreed in June to appoint a special prosecutor, after Cook County State’s Attorney Anita Alvarez recused herself from the case.

The judge announced McMahon’s appointment at a hearing on Thursday.

“It is the state’s burden – it will be, in fact, our burden – to prove this defendant guilty beyond a reasonable doubt. I and this team has one goal in this case. That is to find the truth, to present the truth, and ask that justice be served in this case,” McMahon said outside court after he was sworn in.

McMahon has 24 years of experience as a prosecutor. He began his career as an assistant state’s attorney in 1992, was elected Kane County State’s Attorney in 2010. He also has worked in private practice, and is a lifelong Kane County resident.

Joining his team are assistant Kane County state’s attorneys, Jody Gleason, Dan Weiler, and Joe Cullen. Marilyn Hite Ross, an assistant state’s attorney and criminal bureau chief in Winnebago County, will be the lead prosecutor on the team.

The team has been assigned as special prosecutors in the past in DuPage, McHenry, and Kendall Counties. They have tried a number of murder cases, and reviewed criminal cases against police officers.

Alvarez had initially resisted calls for a special prosecutor in the case, denying her office had any conflict of interest, and defending her handling of the case. However, she reversed course in May, more than a month after losing her bid for re-election in the Democratic primary.

A group of civil rights attorneys and Rev. Jesse Jackson had petitioned Gaughan to appoint a special prosecutor to replace Alvarez, citing her close ties to the Fraternal Order of Police, the union that represents Chicago police officers.

Critics have said Alvarez is beholden to the police union, and has failed to adequately prosecute cases of police misconduct and corruption.

Defense attorney Dan Herbert said he’s prepared to take the case to trial, no matter who the prosecutors might be.

Van Dyke has been indicted on six counts of first-degree murder and one count of official misconduct. He has pleaded not guilty to all charges.

McDonald was killed on Oct. 20, 2014, after police responded to reports of a person slashing tires near 41st Street and Pulaski Road. Police officers surrounded McDonald as he was walking down Pulaski, and Van Dyke shot the teen 16 times within seconds of stepping out of his squad car.

The day after the shooting, police said McDonald lunged at officers with a knife, but dashboard camera video of the shooting released last year showed the teen was walking away from Van Dyke when he was shot. Van Dyke’s lawyer has said the officer feared for his life and the lives of his fellow officers, and the video of the incident doesn’t tell the whole story.

A separate special prosecutor has been appointed to investigate whether other officers at the scene tried to cover up the circumstances of the shooting. Patricia Brown Holmes, a retired judge and former federal and state prosecutor, will to look into whether any officers at the scene lied in police reports to justify a Van Dyke’s decision to shoot McDonald.

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