Drug abuse: A journey to the home of fentanyl, the drug that killed Prince

It’s not just because of the opium that is grown here; it’s also because of its links to the US-bound routes.
“This is the most powerful thing in the world,” he is told.
Filo de Caballos is a hamlet stuck in the backbone of the Guerrero mountains.
Originally created as a potent painkiller for terminal cancer patients, the recreational use of fentanyl has been growing to the point of becoming a nightmare for US authorities.
The drug cartels soon got wind of its penetration in the US.

Fuente: http://elpais.com/elpais/2016/07/05/inenglish/1467716324_130194.html