The parents of 545 child victims of the U.S.’s family separation policy have yet to be located.

Under a zero-tolerance policy, President Donald Trump's administration took the children of illegal immigrants away from their parents pending legal action. Many were not returned.

Though the practice was halted in June 2018 by court order, more than half of the children have yet to be reunited with their families, the Associated Press reports.

Honduran migrants heading north after crossing into Guatemala at Entre-Rios
Honduran migrants heading north after crossing into Guatemala at Entre-Rios AFP / Johan ORDONEZ

Efforts to find the parents were made more difficult by their relocation to their countries of origin.

Volunteers had resorted to going door-to-door in the hopes of finding their families when the COVID-19 pandemic struck, forcing them to halt efforts. Door-to-door volunteering has partially restarted, bolstered by a toll-free Spanish phone line.

In total, at least 1,556 children were separated from their families under the policy. The American Civil Liberties Union, which originally sued the government to halt the practice, says that the committee the court appointed to reunite the families had succeeded for 485 of the 1,030 children that had phone numbers attached to their cases.

The parents of two-thirds of the remaining children are back in their home countries.

Another hearing to discuss the progress of the reunification efforts is scheduled for Thursday.