A judge has cleared 18 more men of drug convictions that resulted from investigations by a reportedly corrupt sergeant with the Chicago (IL) Police Department, according to CBS Chicago.

The exonerations brought to 42 the total number of overturned convictions linked to Ronald Watts since 2016, the Chicago Tribune reported.

Joshua Tepfer—of the Exoneration Project at the University of Chicago—represented 12 of the men exonerated on Monday. He said he has determined from public records requests that more than 1,000 people were arrested by Watts or his team members from 2004 to 2012. Based on the same data, Tepfer estimates as many as 500 of those cases resulted in convictions.

Watts and another officer were arrested in 2012 when they shook down a drug courier who turned out to be an FBI informant. Both pleaded guilty and were sentenced to federal prison. Watts, who received a 22-month term, was released in 2015 and later moved to Las Vegas, records show.

The latest reversals all involve drug cases brought between 2003 and 2008, court records show, according to CBS Chicago. The defendants received sentences ranging from probation to four years in prison—any who were imprisoned were released years ago.