Todd and Melissa Puchalla struggled for more than two years to raise Quita, the troubled teenager they'd adopted from Liberia. When they decided to give her up, they found new parents to take her in less than two days – by posting an ad on the Internet.

Nicole and Calvin Eason, an Illinois couple in their 30s, saw the ad and a picture of the smiling 16-year-old. They were eager to take Quita, even though the ad warned that she had been diagnosed with severe health and behavioral problems. In emails, Nicole Eason assured Melissa Puchalla that she could handle the girl.

"People that are around me think I am awesome with kids," Eason wrote.

A few weeks later, on Oct. 4, 2008, the Puchallas drove six hours from their Wisconsin home to Westville, Illinois. The handoff took place at the Country Aire Mobile Home Park, where the Easons lived in a trailer. No attorneys or child welfare officials came with them. The Puchallas simply signed a notarized statement declaring these virtual strangers to be Quita's guardians. The visit lasted just a few hours. It was the first and the last time the couples would meet. To Melissa Puchalla, the Easons "seemed wonderful." Had she vetted them more closely, she might have discovered what Reuters would learn:

Child welfare authorities had taken away both of Nicole Eason's biological children years earlier. After a sheriff's deputy helped remove the Easons' second child, a newborn baby boy, the deputy wrote in his report that the "parents have severe psychiatric problems as well with violent tendencies."

The Easons each had been accused by children they were babysitting of sexual abuse, police reports show. They say they did nothing wrong, and neither was charged.

The only official document attesting to their parenting skills – one purportedly drafted by a social worker who had inspected the Easons' home – was fake, created by the Easons themselves.

On Quita's first night with the Easons, her new guardians told her to join them in their bed, Quita says today. Nicole slept naked, she says.

Within a few days, the Easons stopped responding to Melissa Puchalla's attempts to check on Quita, Puchalla says. When she called the school that Quita was supposed to attend, an administrator told Puchalla that the teenager had never shown up.

Quita wasn't at the trailer park, either. The Easons had packed up their purple Chevy truck and driven off with her, leaving behind a pile of trash, a pair of blue mattresses and two puppies chained in their yard, authorities later found.

The Puchallas had rescued Quita from an orphanage in Liberia, brought her to America and then signed her over to a couple they barely knew. Days later, they had no idea what had become of her. When she arrived in the United States, Quita says, she "was happy … coming to a nicer place, a safer place. It didn't turn out that way," she says today. "It turned into a nightmare." The teenager had been tossed into America's underground market for adopted children, a loose Internet network where desperate parents seek new homes for kids they regret adopting.

Like Quita, now 21, these children are often the casualties of international adoptions gone sour. Through Yahoo and Facebook groups, parents and others advertise the unwanted children and then pass them to strangers with little or no government scrutiny, sometimes illegally, a Reuters investigation has found. It is a largely lawless marketplace. Often, the children are treated as chattel, and the needs of parents are put ahead of the welfare of the orphans they brought to America.