By Jennifer Pierce, NEWS 9

OKLAHOMA CITY -- A mystery shopper scam is preying on Oklahomans looking to make a little extra money.

Melissa Kerr recently signed up to be a mystery shopper. She never went shopping, though, but she did get a check in the mail.

She was instructed to cash the check, keep a portion for herself to shop and then wire the rest to a person in California.

"I looked at it all. The names didn't match on the check as the one on the email and in my mind I couldn't think why anyone would want me to send $2,900 dollars in cash to a lady in California," Kerr said.

Melissa didn't fall for the scam, but there are people who do.

The U.S. Postal Inspection Service has seen dozens of mystery shopper scams come through Oklahoma. People fall for it, because when the paperwork and check comes in the mail, it all looks real.

"As printing techniques get better, as it gets easier to do these things on the fly in some coffee shop somewhere, then it's going to increase unless we can convince people that it can't be legitimate," said Paul Boyd with the U.S. Postal Inspection Service.

And there are always ways to tell if the deal is a fake.

"You can actually call the issuing bank or the vendor or business that wrote the check," Boyd said.

Usually, the job offers come from one state, and the check from another. In Melissa's case, her check was written from a high school in Washington. She paid attention to red flags, but she worries others may just see dollars signs.

"Especially someone trying to find a little work," Kerr said. "All these people with unemployment, this looks like something easy they could do for quick cash."

If you signed up to be a mystery shopper and received what you think may be a bogus check, call the U.S. Postal Inspection Service office or the state attorney general.