MEXICO CITY (AP) — The University of Notre Dame presented its 2018 Notre Dame Award Monday to a group of Mexican mothers who have led a tireless, yearslong search for missing loved ones.

The volunteer group known as Colectivo Solecito has found clandestine burial pits with the remains of hundreds of crime victims in the Gulf coast state of Veracruz.

Notre Dame President Rev. John I. Jenkins participated in a Mass Monday at one of those sites.

He presented the award to the group’s members for doing everything from fundraising to tromping the countryside looking for burial pits, saying they stood out for “their refusal to remain silent … for their tenacity, and for their faith.”

Lucia Diaz, a group leader, joined the effort after her own son, Guillermo Lagunes, was kidnapped from his home in 2013. No trace of him was ever found. But in addition to his loss, Diaz recounted the dispiriting toil of making the rounds of government offices in charge of investigating the missing, without seeing any progress.

“We quickly realized that the authorities were not going to look for them,” Diaz said. “They weren’t going to find them, and quite possibly they may have even been involved with the kidnappers.”

Drug and kidnapping gangs in Mexico have used pits to hide the bodies of their victims. About 37,000 people are now listed as disappeared.

Due to a lack of modern police procedures, few of the bodies located have been identified so far; while Solecito continues to search for grave sites, the group is now also focused on pushing authorities to identify the bodies found to date.

“There is an opportunity now to learn the truth behind so many deaths,” Rev. Jenkins said. “There is even an opportunity now to find justice and heal.”

The Notre Dame award recognizes international humanitarian efforts; previous recipients include Mother Teresa.