"They're gonna grab these kids and are gonna hold them hostage until they finish the work," DEA Phoenix Special Agent in Charge Doug Coleman told an Arizona NBC affiliate in 2015. "Federal officials estimate it can take nine months or more to build the typical drug tunnel. 'Sometimes they (cartel leaders) pay them. Sometimes they don't. Sometimes when the job is over they will make them disappear,'" Colemen said.
A Mexican soldier removes packs of marijuana inside a tunnel in Tijuana, November 3, 2010.