A prison inmate, who makes stationery and license plates, added a tiny image of what appears to be pig onto a 16-inch decal, which is affixed to Vermont State police cars.
On the decal, there is a cow, and one of the spots on a cow there is the shape of a pig, a slur used for police, reports The Daily Mail.
Andy Pallito, the commissioner of the Department of Corrections, said officials are looking into who made the change, which was added to about 30 police cars (60 decals in total) over the past year.
According to the Times-Union, a Vermont state trooper discovered the pig while inspecting his vehicle on Wednesday.
Pallito said that new police car decals will be made by next week at a cost of $780.
State police Maj. Bill Sheets added: "While some may find humor in the decal modifications, the joke unfortunately comes at the expense of the taxpayers."