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How a mother-daughter crime team turned heartache into millions

It's a case that's ready-made for the big screen. Tracy Vasseur was a divorced mother looking for a new relationship when she started working for Nigerians in a romance scam, according to prosecutors.

"They needed someone in the United States to help the scam. They identified her [Vasseur] as someone who might help them in a big way. And in fact that's what happened," said John Suthers, Colorado's attorney general.

He said Vasseur and her mother wound up scamming hundreds of victims in the United States and 40 other countries. The rip-off, prosecutors found, was in excess of a million dollars.

A call to the Vasseurs' attorney for comment was not returned.

The Vasseur case is just one piece of a massive international business. According to Anthony Roman, founder and chief executive of Roman & Associates, "this is over a $1 billion a year industry and it primarily is centered in Nigeria."

The Vasseur case began in 2009, when she turned to Internet dating sites to find love. Vasseur told investigators she thought she found the perfect man. A U.S. soldier stationed in Afghanistan, who had lost his wife. In recorded police conversations, she said the "soldier" was so convincing, she agreed to wire him money.

Just like countless other romance scam victims, Vasseur was fooled. There was no soldier looking to date the single mom. But instead of nursing a heartache, prosecutors say Vasseur turned to greed.

Vasseur began laundering money for an unnamed Nigerian enterprise, and even enlisting her mother Karen Vasseur to help. Suthers told CNBC, "She became the American military agent so that they, posing as soldiers on the Internet, could tell the people that they were commencing romantic relationships with to ship the money to their military agent in Colorado, which sounds a lot better than shipping it to Nigeria."

For more than three years, investigators say the duo were actively engaged in the Internet romance scam.

According to Suthers, Tracy Vasseur opened up dozens of bank accounts in Colorado to take in cash from unsuspecting women, who thought they were being romanced by soldiers. But when the banks got suspicious, she turned to MoneyGram and Western Union to receive the scammed money from the victims.

Investigators have no evidence the duo ever met with members of the Nigerian enterprise in person. But investigators say Tracy Vasseur was involved in regular and detailed discussions via computer, where she received specific instructions about who was sending money, where it should be sent and how much she should keep for herself. Prosecutors added money was picked up at multiple locations in Nigeria.

The scheme was busted when complaints started rolling into Colorado authorities. Investigators said the complaints were from victims who had wired money to the Vasseurs.

The pair were eventually convicted of racketeering and theft from at-risk adults, and sentenced to lengthy terms behind bars. Tracy Vasseur is serving 19 years at La Vista Correctional Facility in Pueblo, Colo., and Karen Vassuer is serving 12 years at the Denver Women's Correctional Facility.

—By CNBC's Andrea Day. Follow her on Twitter @AndreaDay.