5 Facts About Immigration Policy Separating Children From Parents, 1,475 Missing Children

3. HHS says not responsible to find missing children, some may have deliberately gone 'off the grid.'

The Washington Post also reported Sunday that officials at HHS have maintained that it is not the legal responsibility of the agency to locate those children once they are released from the care of the Office of Refugee Resettlement.

Adult sponsors are sometimes relatives who already were living in the United States and who intentionally may not be responding to contact attempts by HHS. Vox reporter Dara Lind pointed out on Twitter that amid the fury over the HHS Senate testimony mentioning the children had gone missing that "we do not know how many of these children weren't located because they and their relatives in the US (who might even be their parents!) made the decision to go off the grid to reduce deportation risk."

Some have raised the possibility that those kids have wound up in the hands of traffickers, an idea bolstered by a PBS "Frontline" report that aired on April 24 about trafficking in the United States. The episode traced how eight children were forced to work at an egg farm in Ohio.

Senator Rob Portman of Ohio, who is known for his advocacy on human trafficking issues, criticized HHS in the PBS special.

"We've got these kids. They're here. They're living on our soil," he said in the interview.

"And for us to just, you know, assume someone else is going to take care of them and throw them to the wolves, which is what HHS was doing, is flat-out wrong. I don't care what you think about immigration policy, it's wrong."