By Channing Joseph

Jason Van Dyke, the white Chicago police officer charged Tuesday (Nov. 24) with first-degree murder for the fatal shooting of black teenager Laquan McDonald, has a history of using excessive force and racial slurs on the job.

That’s according to researchers at the University of Chicago and the nonprofit Invisible Institute, which has recently published a database containing more than 50,000 previously unknown complaints against Chicago police officers.

Van Dyke, a 14-year-veteran of the department, has received 18 complaints against him, including one dated Oct. 20, 2014, the night he killed 17-year-old McDonald after a videotaped confrontation in which McDonald is seen holding a knife but does not appear to pose any immediate threat to the officers.

The release of the video this week has sparked mass demonstrations in Chicago.

“We don’t have all of Van Dyke’s complaints,” Alison Flowers of the Invisible Institute told Chicago ABC affiliate WLS, but “the misconduct complaints from Van Dyke that we do have in our data tool show by and large excessive force and racial slurs. And he has largely operated with impunity and under a code of silence with the same huddle of officers again and again.”

None of the complaints against Van Dyke resulted in any penalty. In four of the cases, the officer’s actions were deemed lawful, and in most of the others, there was either not enough evidence to prove or disprove the allegation or the claim was proved untrue, the Washington Post reports.

Ed Nance, a cable company worker who had no criminal record, filed a complaint against Van Dyke in 2007 for excessive force after Van Dyke injured Nance’s shoulders during an aggressive arrest at a traffic stop. The officer was later cleared of wrongdoing, but a federal jury award Nance $350,000 for his injuries.

When Nance learned early this year that Van Dyke was the officer involved in McDonald’s shooting, he told the Chicago Tribune: “It just makes me so sad because it shouldn’t have happened. He shouldn’t have been on the street in the first place after my incident.”

“It makes me feel like it could have been me,” he added.

Van Dyke is the first Chicago police officer to be charged with murder for an on-duty shooting in more than 30 years.