The Justice Department has arrested 21 people suspected of belonging to a theft ring that made more than a half billion dollars from stolen catalytic converters.

Fifteen of the defendants are accused of buying catalytic converters from local thieves and shipping them to DG Auto in New Jersey.

Six people of DG Auto are accused of buying the stolen parts and "de-canning" them to extract the powdered metals—rhodium, platinum, and palladium—and sell them to a metal refinery. They allegedly made about $545 million from the process, the Justice Department said.

A team of law enforcement agencies at the local, state and federal levels seized hundreds of millions of dollars in assets, such as homes, bank accounts and cash, cars and jewelry from the defendants. They are being charged with conspiracy to transport stolen catalytic converters, conspiracy to commit money laundering, and more, NPR reports.