GRASS VALLEY (CBS13) — Prosecutors are saying a small-town jeweler is a big-time crook who sold bogus silver and gold bars to dozens of unsuspecting customers.

Tax charges could be added to an already long list of felonies the owner of Grass Valley Gold & Silver is facing.

Prosecutors say three more victims came forward last week, bringing the number to nearly 40 who were allegedly tricked out of a combined $400,000 by Greg Arnoldi.

A gold bar looks pretty on the outside, but as John Engelhardt’s tester proves, the gleaming gold is only skin-deep. It’s a thin coating concealing a bar made of brass.

“Garbage,” he said. “There was a lot of people, a lot of people got burned—lotta old folks.”

The story first hit the papers in February when Arnoldi was arrested for allegedly selling bogus bars.

Now customers are still coming into Engelhardt’s shop around the corner to have their supposed gold and silver tested. He’s had to deliver the bad news to dozens before sending them to the Nevada County district attorney.

“A lot of them are old,” he said. A lot of ’em can’t afford it. A lot of ’em—their savings, everything they had to retire is gone.”

Jay Dendy met Arnoldi after two men broke into the gold and silver shop. He said Arnoldi won him over completely.

“If I had a desire to buy gold or silver, I’d have bought it from this guy. He had my confidence,” he said.

CBS13 interviewed Arnoldi’s wife, Shara, after the April 2014 burglary. Prosecutors say not only did her husband get caught, but she’s been arrested on welfare fraud charges.