It's a mother's nightmare. She returns home one day and finds no trace of her only child, and the apartment she shares with the 18-month-old boy's father is ransacked. There are no baby clothes, no papers, no photographs, not even an ultrasound image of her son, Steven.

Twenty-one years ago, Maria Mancia of Rialto, Calif., first thought that she had been robbed. Then she noticed that other belongings were gone, too, and she soon realized that her boyfriend, Valentin Hernandez, had abducted their son and fled to Mexico. She reported the boy missing. But as the years passed, she had to accept the growing likelihood that she would never see him.

Her only memento was a grainy photograph sent to her by relatives in El Salvador that she could show to police.

But last week, Mancia's nightmare finally ended when authorities brought her some stunning news.

"Some detectives came to my house, and at first I was scared because I didn't know what was going on, but then they told me they found him. They found Steven," she told The Sun newspaper in San Bernardino, Calif.

Mancia and her now 22-year-old son were reunited this week after he crossed the border from Tijuana, Mexico, led by investigators from the San Bernardino County District Attorney's Office. They met face to face just before a press conference in San Bernardino.

County authorities had been looking for the boy for years, but the case grew cold until recently when investigators with the Child Abduction Unit received a credible tip that he was living in Puebla, Mexico. His father was missing and presumed dead, authorities said. They decided to approach Steven Hernandez without raising expectations.

"We didn't want him to know what was going on," Senior Investigator Karen Cragg told The Associated Press. "We didn't want to scare him off. We weren't sure what the circumstances were down there. We had to tread very carefully."

So they developed a ruse, telling Hernandez they were investigating his father's disappearance, and asked for a DNA sample. Officials at the U.S. Department of Justice confirmed it was a match with his mother.

"It was a shock," Hernandez told the Sun. "I didn't know if she was alive or not and to get a call that says they found my mother and that she had been looking for me, it was like a cold bucket of water. But it's good. It's good."

Hernandez said what little he knew about his mother was what his father had told him — that she had abandoned the family. Now he's learned that he has four siblings. It's still not clear what happened to his father.

Hernandez was a law student in Mexico. But since he was born in the U.S. and is a citizen, he plans to stay and seek a legal career here.

Copyright 2016 NPR. To see more, visit