Ricardo Salazar Sanchez boarded a northbound bus in the central state of Guanajuato with 22 fellow residents for a journey to the U.S.-Mexico border—and a subsequent attempt at crossing into Texas, where potential construction jobs awaited.

The men, who left March 21, never arrived.

What happened to them remains a mystery. In April, family members began suspecting the men ended up in the mass graves discovered on a ranch near the U.S. border; authorities found the remains of passengers pulled, at gunpoint, from northbound buses by the Mexican drug gang Los Zetas.

“We started to worry because on the news they said the bodies ... hadn’t been there very long,” said Minerva Hernandez Guzman, Salazar’s wife.