Illinois law enforcement officials say they’re putting a dent in an auto theft ring that stretched across the Chicagoland area.

Illinois Secretary of State Jesse White said police recovered about 200 stolen Cadillacs, Land Rovers, Mercedes Benz and BMWs worth about $4 million.

The joint investigation began after an employee in White’s office noticed a number of fake out-of-state titles on applications for valid Illinois titles. Investigators in White’s office, state police and Cook County States Attorney Anita Alvarez’s office worked to bring down the network of criminals.

Authorities say the thieves sometimes stole cars from dealerships across Cook, DuPage, Will and Lake counties by posing as transporters that move cars from place to place.

They then sold them on the street or on Craigslist.

Investigator Elmer Garza says they created fake vehicle ID numbers, or VINs.

“Then they create the title document to reflect that VIN number and submit it to our office,” Garza said.

Two ringleaders—a father and son, James Henley and Dominique Henley—have been sentenced, and 13 others have been charged.