It took 85 days for Olivia Caceres to retrieve her baby boy, pulled from his father's arms at the U.S. border, a traumatic experience many more parents face to reunite with children separated under President Donald Trump's immigration policies.

Now nearly 20 months old, Mateo was returned to his family on Feb. 8 after a battle across borders, officialdom and languages. He was filthy and terrified of the dark, his mother said. Months later, the boy still screeches even as Caceres rocks him on her chest, sometimes until dawn.

The Salvadoran family's story of struggle in U.S. immigration detention presaged what was to come: Trump's "zero tolerance" policy that led to more than 2,300 migrant children being separated from parents in recent weeks.