A trio of Mexican brothers, thought to be Sinaloa Cartel operatives, await execution by hanging in Malaysia following a conviction on drug trafficking charges.

Luis Alfonso, Jose Regino, and Simon Gonzalez Villarreal were arrested at a laboratory in 2008, where authorities say they found $15 million worth of methamphetamine. Lawyers for the Mexicans have maintained that they had nothing to do with the illegal drug production at the lab, but an appeal to have the conviction tossed out was denied earlier this week.

The three brothers are natives of Culiacan, Sinaloa, a region with deep historic links to the drug trade. They had been lifelong brickyard employees, before receiving the offer to move abroad a little more than three years ago. “I think they had no idea what they were getting into,” Israel Gonzalez Villarreal, an older brother still living in Mexico, told the Associated Press.

The brothers are thought to have been working for the Sinaloa Cartel, one of the most aggressive Mexican organizations in forming links to Asian suppliers of meth and precursor chemicals used in its production.

The Gonzalez Villarreal brothers were not known as members of organized crime while in Mexico, though authorities say that it’s not uncommon for relative novices to be placed in charge of meth labs, as the operation is relatively simple.