On the crowded streets of Ho Chi Minh City, Vietnam, advertisements selling U.S. marriage visas are as common as ads for produce at grocery stores, according to federal agents.

On Tuesday, federal immigration agents announced the breakup of what they call Utah's largest marriage visa fraud ring ever. As the result of an 18-month investigation called "Operation Morning Glory," 24 people, mostly naturalized Vietnamese residents living in Utah, were indicted on 79 counts of conspiracy, alien smuggling, marriage fraud and aggravated identity theft.

U.S. Attorney for Utah Brett Tolman said the cooperative investigation between his office, U.S. Immigration and Customs Enforcement (ICE), the U.S. Citizenship and Immigration Service and others netted an operation in which single Utah residents were recruited and paid between $50 to as much as $10,000 to marry Vietnamese citizens for the purpose of gaining U.S. citizenship for them. Tolman said people in Vietnam were willing to pay as much as $30,000 for the fraudulent marriages.

"The scheme alleged in this indictment takes the concept of 'arranged marriage' to a new level," Tolman said. "Those charged in this indictment exploited a process intended to assist families. Their subversion was motivated by greed."

As of Tuesday, 21 of the 24 suspects had been taken into federal custody, including five identified as ring leaders of the operation:

• Hoa Thanh Vo, 40, West Valley City

• Henry Ngoc Nguyen, 45, West Jordan

• Buu Van Troung, West Jordan

• Ngoc Hoa Huynh, 33, West Jordan

• Danh Huy Do, 33, West Valley City

Federal officials said the investigation, which also expanded overseas to Vietnam, found the ring allegedly paid Utahns to travel to Vietnam, where they would take part in an "engagement ceremony" with the paying customer.

The couple would then change clothes several times in a day and be photographed at various locations to show U.S. immigration officials that they had been in a long-term romantic relationship. Couples typically have to be married for more than two years and be subjected to individual interviews by immigration officials before a foreign national can qualify for citizenship.

Mario Ortiz, the Denver district director for the U.S. Citizenship and Immigration Service, said the group's operation cheapens the laws intended to keep true married couples united.

The 259,144 immigration visas obtained through marriage in fiscal year 2005 accounted for nearly a quarter of the green cards, according to CIS data.