SAN DIEGO -- Six months after Barbara Martinez's son disappeared, the nightmares began.
"I would close my eyes, but then I would see him buried under the ground, but with his eyes open, and stuck there; looking up at me like this," Martinez said Thursday, making a face to show how she imagined her dead son shot desperate looks at her from beneath the blackness of his undiscovered grave.
She couldn't sleep or eat. She could only think about finding her son.
Cesar Ezequiel Rico de la Cerda, her 17-year-old child, disappeared from Tijuana's southeast Urbi Villa Del Prado II neighborhood in October 2018.
Martinez is now among thousands of parents and family members who have formed collectives throughout Mexico to help each other search for the remains of their missing children. It's a response to what they describe as failure by the Mexican government to protect or search for their missing children.
Although Martinez believes her son's remains are located in a home in Tijuana, she travels to places like Poza Rica, Veracruz, near Mexico's eastern coast as an act of solidarity with members of her group, the "Collective of Mothers Searching for their Lost Treasures."
Parent groups spend weeks at a time searching rugged and remote areas nationwide for clandestine mass graves, known as fosas clandestinas.
Last week, the groups descended on remote hills in eastern Tijuana after discovering dozens of bodies buried there. As is often the case, it started with an anonymous tip to one of the parent organizations and directions to an isolated burial grounds -- a place where criminals know they can discard bodies, according to the president of one of the collectives.
"It was a phone call to my colleague ... who was given an exact point where he would find a body," said Jesus Varagas Chairez, a Riverside resident and president of Buscando a Tolando, or Searching for Tolando, his missing brother.
A few of the men went first on the search, well aware the area was likely guarded by armed cartel members.