Bay Area authorities on Wednesday night were asking for the public's help catching a man who has stolen thousands of dollars elderly victims with a promise of gold that's too good to be true.

The latest scam happened at the Castro Village Shopping Center in Castro Valley.

Alameda County Sheriff's Department investigators said a man took an elderly woman for $7,000 in the parking lot of the shopping center.

They said he told the woman a story about needing money to care for a sick relativem and then he sold her a gold bar that turned out to be fake.

The suspect is described as clean cut and was dressed in hospital scrubs, but the sheriff's office said he is a man with a heart made of anything but gold.

Investigators said he told an elaborate story to convince his victim to withdraw money from a bank.

"[He said] they need money fast and they have a gold bar or gold bars that they want to exchange for cash," said Sgt. J.D. Nelson of the Alameda County Sheriff's Department.

Investigators said the same individual may be responsible for similar crimes using fake gold bars in San Mateo, San Jose and Salinas. Those crimes have scammed victims out of  $5,000 to $15,000 at a time.

In some cases, investigators said the scam is as simple as spray painting an everyday brick gold. The prop is apparently convincing enough to get some people to hand over thousands of dollars.

Some area residents found it hard to believe that anyone could be tricked so easily.

"I think it's just ludicrous and I'm really sad to hear that so many people would fall for that obvious a ruse," said Frank Burton of Castro Valley.

Nelson agreed.

"What he's doing is he's scamming old people," said Nelson. "It's a despicable act and we'd like to get him behind bars."

Investigators worry there could be other cases that have gone unreported because the victims are too embarrassed to admit they were tricked.