Osiel Cárdenas Guillén (born 1967) was the leader of the Gulf Cartel who made one of the most consequential decisions in Mexican drug war history — recruiting former Mexican special forces soldiers to serve as his personal enforcers. This group became the Zetas, who eventually broke away to form their own brutal cartel. Extradited to the US in 2007, he was sentenced to 25 years in prison in 2010.

Reference:

Osiel Cárdenas Guillén on Wikipedia

https://en.wikipedia.org/wiki/Osiel_C%C3%A1rdenas_Guill%C3%A9n