DALLAS -- Postal inspectors are warning unsuspecting people about a new confidence scheme. The scam involves altered or counterfeit postal money orders and has spread across the United States, including North Texas.

Investigators said about 30 to 40 people have fallen victim to the scam, and officials think more unreported cases have victimized an unknown number of people.

The scheme typically begins with communication through an online chat room. A scammer will ask a targeted person to accept a money order, usually sent by an overnight delivery service if the target agrees.

The scammers will ask the targeted individual to cash the money order, keep a portion of the amount and return the balance to the originator of the message. Postal inspectors said the money orders either are counterfeit or genuine that have been altered to reflect a greater amount than originally purchased.

Debra Cudd, of Grand Prairie, Texas, fell victim to a man she corresponded with in an online chat room. The man claimed he would send her money for a ticket to Hawaii.

"He said, 'I've got some clients that owe me some money. I'll have them send you the money orders. You cash them, take out what you need for the airfare and then wire me the rest,' " Cudd said. "I learned my lesson."

She received three money orders, each bearing the amount $950. She learned all three were counterfeit when she tried to cash them.

Inspectors believe the scheme originated in West Africa, which makes investigations and prosecutions difficult.

"It's very organized," Kenny Smith, a U.S. Postal inspector, said. "We're talking about people who are overseas who are taking advantage of individuals in the United States by duping them with money orders that are either counterfeited or altered in some way."

Smith also said the money orders, whether counterfeit or altered, are extremely high-quality replications.

"The commercial-grade printing that's being used when it comes to these money orders looks so good it would appear to be a very organized gang that has a tremendous amount of resources to further this scheme," Smith said.

Investigators said victims of the scam could be out a significant amount of money or face legal action if they try to cash the bogus money orders.