A former Gwinnett County police sergeant has been arrested on racketeering and forgery charges related to a used-car selling scheme, authorities announced Friday.

Michael James Saunders, who resigned from the department last month after 18 years of service, was allegedly buying and selling used vehicles without a dealer's license, said Cpl. Illana Spellman, spokeswoman for the Gwinnett County Police Department. Georgia allows a maximum of five vehicles to be sold privately each year without a license.

Saunders, 48, is also accused of forging signatures on documents involving the ownership of his vehicles.

Police said a citizen complaint to the internal affairs unit prompted an investigation which lasted two months, culminating in Saunders' arrest Thursday at his home in Duluth.

Saunders is charged with one count of first-degree forgery, two counts of violation of oath of office, one count of racketeering, one count of false statement in application and three counts of illegally selling used vehicles.

Saunders was a shift supervisor for the South precinct in Lilburn. The South Precinct serves a 116 square mile area in the the southwest corner of Gwinnett, which includes the city of Grayson as well as unincorporated areas of Tucker, Lilburn, Stone Mountain, Centerville, Snellville, Loganville, and Lawrenceville.

He is being held on $103,900 bond at the Gwinnett jail.