Administration officials conceded last year they had “no way” to reunite most migrant families, who had been separated at the border, according to emails obtained by NBC News.

“[I]n short, no, we do not have any linkages from parents to (children), save for a handful,” a Health and Human Services official wrote to an official at Immigration and Customs Enforcement on June 23, 2018. “We have a list of parent alien numbers, but no way to link them to children.”

The email and others were provided to NBC News by the House Judiciary Committee.

The problem resulted in a months-long effort to reunite almost 3,000 families separated after the administration’s “zero tolerance” policy, the network news said. All relevant records had to be reviewed manually.

As many as 55 children are still in Health and Human Services custody in shelters. The lack of data has resulted in problems locating other children. NBC News said the numbers could potentially be in the thousands.

President Donald Trump ended the separation policy June 20, 2018. The Department of Homeland Security said at the time the government knows the location of all the children in custody.

However, there was no database with information for both children and their parents. And some key information was missing completely, according to NBC News.