And in the end, they were spending their own money to purchase their own merchandise back," said Todd Williams, the Homeland Security agent.
For the textbook scam, the group targeted family owned businesses and many went out of business.
As the crime ring operated, they began to get more sophisticated and relied on prepaid cards to move money, instead of e-mules.
"They not only would purchase the textbooks with compromised credit cards, but in most instances, within 48-72 hours from purchasing the textbooks, they would actually sell the textbooks back to the same textbook company online that they stole the books from.
So essentially these textbooks companies were getting the merchandise stolen from 'em.
Prosecutors in Gulfport, Mississippi, recently took down one Nigerian crime ring that brought in $52 million. I got a call from my wife that someone had come onto our property looking for me," said the agent, who spoke to CNBC on the condition of anonymity.
For one former government agent, that scam began with a woman showing up at his door. "The person told my wife that she had met me with my name" on a dating website.
Its high rate of subscribers engaging in romantic relationships and meeting live partners makes it a one-stop dating site.