"Do you want to take my daughter?"

Convicted baby trafficker Duan Yueneng uttered those words moments after I stepped into his apartment to interview him. As far as I could tell (and my assistant Cecilia Chen next to me), Mr. Duan was not kidding. His daughter, by the way, stood about five feet away. This man has been busted for selling Chinese baby girls, and he's trying to offload his own child. I declined.

"My second baby was a girl," Duan said. "Because the one-child policy was very strict then, I wanted to get rid of her, so that I still have a chance to have a baby boy. After all, you need to have a boy.

"My mother didn't want to abandon her, nor did my mother-in-law. I tried a couple times putting my second daughter on the street but nobody wanted her. I finally took her back. Now she's 15 as you see."

Illegal adoptions a 'demand-driven market'

Duan kept a straight face throughout the interview. He described the international adoption economy as a demand-driven market. Parents from America and elsewhere wanted to adopt Chinese infants. These parents paid $3,000 to the child's orphanage, under Chinese rules. Naturally, orphanages supplied babies, in some cases buying babies from Duan, the supplier.

His mother was part of the action, too. She was transporting infants from Zhanjiang, Guangdong -- where they bought babies from another supplier -- to Changning, Hunan. A 600-mile trip.

"We put six babies in three big powdered milk cardboard boxes," Duan's mother told us during the interview. "We put two babies in each box. My daughter went with me. We boarded the train at Zhanjiang station. In the middle of the trip, one box fell. Then, I started feeding them, one after another. Each of us was holding one baby and we had other four babies in two boxes."

Exposing the paper trail

Then came the documents from Duan's official court file. Orphanage receipts revealed when babies changed hands and for how much. Bank transfers accompanied the receipts, often the money went to an account in the name of Duan's aunt. Orphanage logs showed when infants arrived, and who brought them. Often the deliverer -- the official baby finder -- was one of Duan's sisters. Or his mother. In other words, these babies were not found in the neighborhood by a good Samaritan, as the typical narrative would put it. They were sold to the orphanage.

The papers we saw -- just a portion of Duan's court file -- showed at least one baby delivered by the traffickers was adopted by an American couple. We saw their names, their adoption papers, official copies of their passports, but chose not to name them in the story. What if they don't want to know?

Breaking through China's lack of transparency

When I moved to China in early 2007, a fellow foreign journalist described China this way:

"It's like looking through three panes of glass. You can't get very close." Indeed, it can be maddeningly difficult to get near the real action, the real players.

In this case, many sources spoke to us on condition of anonymity. The Chinese government refused to talk for the record, as did every orphanage director we tried. We called the lead adoption ministry in China several times before someone even confirmed basic facts about Chinese adoption policy. We showed up at one Hunan orphanage, and after the director sat us down, offered us tea and took our business cards, he declared himself "too busy" for an interview.

Even basic adoption and orphanage numbers are scarce: one Chinese scholar in the field told us this is such a sensitive topic even he can't get access to the numbers.

Research shows the problem might not be getting much better. Dutch social worker Ina Hut says we may never know even if it does. Hut used to direct the largest adoption agency in Holland. When the Hunan scandal broke, Hut told me she sought an independent investigation in China, to see if any trafficked babies ended up going to Holland. She says Chinese officials denied her, as did her home government. When Hut pushed the issue, she says Dutch officials warned her it would endanger relations with China. And, she says, Dutch officials vowed to revoke her agency's adoption license if she persisted. Hut quit last year in protest.

For more on this story, listen to my radio report and read more reactions from American families with adopted Chinese babies.