Source:
Christian Science MonitorMr. Oliva Castillo is an alleged top leader of the Zetas drug group, and more significant, the alleged mastermind of the arson attack that killed 52 people in a casino in August, most of them middle-aged women.
The casino attack, in the northern city of Monterrey, is largely considered to be one of the most horrific acts of violence in Mexico, since Mexican President Felipe Calderon took office in 2006 and announced that federal forces would fight drug traffickers.
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http://www.csmonitor.com/World/Americas/Latin-America-Monitor/2011/1013/Mexicans-unite-over-arrest-of-alleged-leader-in-Los-Zetas-cartel