Last week, Megan Twohey of Reuters published a major investigation about how American families use Internet message boards to abandon difficult children adopted from other countries. Twohey showed how exasperated families use Yahoo and Facebook groups to find new parents for the children they swore to take care of. And far too often, these children end up in homes where the guardians have not been approved to take care of children, where they can be sexually abused or put in surroundings that are dangerous for their well-being.

ProPublica reporter Marshall Allen sat down with Twohey to get the story behind the story of piecing "The Child Exchange" together. Asked to describe how she got started, Twohey said, "One of the most valuable things I think about this project is I worked with our database team. We basically did a deep dive on one of the Yahoo groups where this - it's called re-homing - activity takes place. And we scraped all 5,000 messages going back five years and built a database where we were able to quantify what was going on. We logged every single offer of a child that was being made over a 5-year period and we found that on average a child was being offered up once a week."

Twohey added, "It's interesting to note too that the term ‘re-homing’ was first used to describe people seeking new owners for their pets. And some of the ads read remarkably similar to the ads that you'd see for people trying to find a new home for their pet. Some of the ads would describe kids as being obedient, eager to please, or talk about them being pretty."

Read the five-part investigation at Reuters.com and you can listen to this podcast on iTunes and Stitcher.