MARION, Ill. (AP) — A southern Illinois judge who went to Chicago for a temporary assignment and ended up helping convict dozens of judges, attorneys and police officers in one of city’s most famous corruption cases has died.

Brocton Lockwood died Monday in Marion after a fight with Parkinson’s disease. He was 74. Crain Funeral Home & Cremation Service confirms the death and says no services are planned.

Lockwood filled in on the bench in Chicago in the early 1980s, something downstate judges did to help reduce a backlog of cases in Cook County.

But in 1981, he alerted federal authorities to widespread corruption. He wore a wire and taped conversations for three years with corrupt judges, lawyers, court employees and police officers.

The investigation known as “Operation Greylord” led to the conviction of nearly 100 people.

Lockwood later told the (Carbondale) Southern Illinoisan newspaper that he hid a recorder in his cowboy boots.