Four Americans at the heart of an adoption scam that tricked Samoan families into giving up their children have escaped jail time in the United States.

US investigators travelled to Samoa and New Zealand to unravel the case against the Focus on the Children agency which adopted out 80 Samoan children between 2002 and 2005.

The agency told the parents the children would be educated in the US, and could return home when they were 18.

But the agency told the American families they were orphans and accepted thousands of dollars for them.

The editor of the Samoan Observer newspaper, Keni Lefa, told Radio Australia the judicial leniency would come as a great shock to the parents of the children.

Scott Banks, 47, Karen Banks, 48, Coleen Bartlett, 52 and KaraleeThornock, 36, received 60 months probation as part of a plea agreement in which they and their agency admitted various immigration, visa and fraud charges.

Focus on the Children was ordered dissolved.

As a part of the plea agreement, the agency agreed to cease involvement in domestic and international adoptions.

The defendants will also pay into a trust fund to help communication between the adoptive families and birth parents.

A 2007 federal indictment charged the defendants with 135 counts of conspiracy, fraud and immigration violations covering the adoption of 37 children between 2002 and 2005.

But the US Attorney for Utah, Brett Tolman, said this week a traditional criminal case resolution would have not resolved the issues for the children and families involved.

Cases are still pending against three other defendants.

Daniel Wakefield, 72, will be sentenced in March for helping locate children in Samoa.

But the Samoan Government has not allowed extradition of two citizens, Tagaloa Ieti, 46, and Julie Tuiletufuga, age unknown who are still sought by US authorities.

The US TV network ABC reported one adoptive parent, Michael Nyberg found the four year old he named Elleia, started saying the names of her parents and siblings, talking about how they all slept in a house together, even though the adoption agency said she had been abandoned by her family and left in foster care for months.

"She started talking about things that didn't add up," he said.

He returned the girl to her Samoan family - who had named her Sei and had never planned to give her up.

Wisconsin single mother Patti Sawyer was told the girl she adopted was found in a public toilet.

"In reality, she was from a very happy family, eight brothers and sisters," she said.

Ms Sawyer said she was concerned that if she took her adopted daughter back to Samoa to visit her biological family, she might not be able to take her out of Samoa to return to the US.

She hoped to convince the girl's Samoan family to let her finish her education in the US, visit home, and share her life with two sets of parents.