TOLEDO, Ohio (AP) — Four people accused of operating a large-scale fake ID operation that netted investigators $4.7 million in bitcoin have been indicted by a federal grand jury in Ohio.

The four from the Toledo area are facing federal charges announced Thursday that include making false identification documents and possessing document-making equipment.

The group was arrested in early February after investigators seized bitcoins, computers, printers and gold and silver bars inside a Toledo home.

Ohio authorities began investigating in 2015 after receiving several fake ID cards from a bar in Springfield. A college student told investigators his friends bought IDs from the online social forum Reddit.

Documents say buyers had to follow specific instructions to hide the transactions and use bitcoins, digital money that isn’t tied to a bank or government.