Federal agents are continuing to unfold a major child porn network, so far spanning as far as the Netherlands.
To date, 43 men have been arrested in the investigation that has been underway for two years.
Authorities identified more than 140 young victims and fear there could be numerous others after sifting through hundreds of thousands of images on the suspects' computers.
"They are the worst of the worst," said Bruce Foucart, agent in charge of the U.S. Customs and Immigration Enforcement agency's Homeland Security Investigations unit in Boston. "This isn't just a child that's nude and someone's taking pictures of him; this is a child that's being raped by an adult, which is horrific."
Among them is Robert Diduca, a hotel manager in Massachusetts, and Robert Mikelsons, a day care worker who sexually abused an 18-month-old boy in his care.
The case unfolded when Diduca sent a photo of the infant holding a stuffed bunny to an undercover agent. Dutch police recognized the bunny and placed the photo on a program similar to "America's Most Wanted."
Within minutes, the parents of the boy got calls about the picture.
Eventually, Mikelsons was arrested. The photo of the boy was found on his computer, along with thousands of others.
Photos and online chats found on computers belonging to Diduca and Mikelsons led to more than three dozen other suspects in seven countries, including Canada, Britain, Germany, Sweden and Mexico.
One victim was just 19 days old.
Parents of the victims are finding it difficult to deal with the horrific news.
One mother recalled thinking, "You guys got the wrong guy," when authorities said a long-time family friend sexually abused her child.
"I had no idea," she said. "It's depressing."