"This case is about a criminal conspiracy inside one of Wall Street's largest banks," said Lucy Jennings, a prosecutor with the Justice Department's fraud section. "To make more money for themselves, they decided to cheat."

The trial of three former JPMorgan employees, including the veteran head of precious metals, Michael Nowak, is the most ambitious effort yet in a years long US crackdown on market manipulation and spoofing. Unlike past cases of alleged trading fraud, the trio is accused of a racketeering conspiracy under the 1970 Racketeer Influenced and Corrupt Organizations Act -- a criminal law more commonly used against the Mafia rather than global banks.

Nowak, gold trader Gregg Smith and Jeffrey Ruffo, an executive director who specialized in hedge fund sales, are charged with racketeering conspiracy as well as conspiring to commit price manipulation, wire fraud, commodities fraud and spoofing from 2008 to 2016. All together, Nowak and Smith have been accused of more than two dozen crimes. The three defendants face decades in prison if convicted on all counts. Another trader, Christopher Jordan, who was charged alongside them, is scheduled to go to trial in November.