Chen Chiang Liu and Min Li Liu were charged with passing counterfeit $100 bills through slot machines at Caesars. They subsequently exchanged the comforts of their resort room for a jail cell.

The Lius possessed more than 400 counterfeit $100 bills when they visited Caesars Palace between July 26 and July 31, according to the indictment.

The couple unwittingly helped security officers with their investigation. While stuffing counterfeit bills into slot machines, the pair played rewards cards, which, experts said, are tied into a database that includes personal information about each registrant, including each player's home address.

"In this case, what I think got these people caught was their greed," said Douglas L. Florence Sr., a surveillance and gaming operations expert. "They wanted to get their points, and they wanted to get money. They narrowed down the list of suspects."

Caesars officials declined to comment on the investigation. But according to a federal complaint filed July 30, security officers identified 13 slot machines that accepted a total of 60 phony $100 bills. After discovering each machine was played with the same player's card, officers reviewed surveillance cameras and identified the couple.

Florence said any counterfeiter who passes the bills in a casino while using a player's card registered in his or her own name is either stupid with greed or "flat out wants to be caught."

The player's card launches investigators over one of their first hurdles and makes the next step that much easier. "It's now a matter of surveillance proving they put (counterfeit) money in," Florence said.

The Lius were stopped when they tried to leave Caesars on July 30, the complaint said. The U.S. Secret Service, which is tasked with handling of investigations regarding counterfeit money, was called in to help with the investigation.

Agents searched the Lius' Cadillac Escalade and found three red bags stuffed with about $30,000 in counterfeit $100 bills, the complaint said. Chen Chiang Liu told the Secret Service that the money was a debt an acquaintance paid back to him, according to the complaint.

Liu said he was unaware that the money was counterfeit.

Agents found $23,800 in genuine currency in Min Li Liu's makeup bag. They discovered an additional $2,900 in bona fide bills in her wallet.

"When asked why she was carrying an aggregate sum of $26,710 in genuine currency, Min Li Liu stated it was from game winnings, however Min Li Liu would not be specific about where or when the winnings occurred," the complaint said.

Min Li Liu also had in her possession tax receipts from jackpots she hit during the weekend. The total amount of winnings documented on the forms amounted to $17,600.

The government alleges the Lius used the fake cash to wager bets, then cashed out and received legitimate money. They also hit a few significant jackpots while playing with the bogus money or legitimate money they had obtained with the counterfeit money, according to the indictment.

Calls to federal public defender Arthur Allen, named in court documents as the Lius' attorney, were not returned.

According to the complaint, the couple used exceptionally high-quality counterfeit cash.

"Due to the high quality of this counterfeit, cash validators used in casino slot machines do not detect the counterfeit $100 Federal Reserve Notes," according to a federal complaint filed July 31.

Florence said the Caesars case is not the first time counterfeiters have hit Las Vegas casinos.

Florence captured a gang of visitors who fed slot machines at The Mirage counterfeit bills. They immediately cashed out and redeemed the coins for real money. He recovered $35,000 from the visitors' hotel room and the casino was reimbursed for the counterfeit play.

If suspects are never caught, the casinos have to absorb the loss, Florence said.

Bill validators on slot machines are not set to catch fake bills; if they were, genuine money that might be tattered would be rejected, said a gaming source who asked not to be named. Customer service would suffer if bills were routinely rejected.

The high-tech bill validators are located in the count room, where money handlers meticulously feed bills from slot boxes into a machine. Counterfeit bills are easily detected, the source said.

"We do catch it more often than not in the count room because the caliber of machine is cranked to the highest level," the source said.

Florence added that if the bills are found in the count room, security can direct surveillance cameras to the machines from which the phony money was collected. Criminals often return to the same machine because it accepted the fake bills the first time, he said.

Gamblers who try to pass counterfeit money in Las Vegas casinos are foolish, Florence said, because of the number of cameras set up throughout the casino floor. They are bound to be caught, he said.

According to the Secret Service, from April 24 through July 30, agents recovered about $80,000 worth of counterfeit bills that were passed through slot machines and cashed out for real bills. During that same period, agents recovered about $123,400 in distinctive counterfeit $100 bills from casinos and Las Vegas businesses, the complaint said.

Secret Service representatives declined to comment for this story, saying the investigation is ongoing. Ken Langdon, a spokesman for Caesars Palace, did not return phone messages.