WHYS60: Who's afraid of the Mexican drug cartels?

Available for over a year

"This is going to happen to all the internet busybodies,'' read the note - signed Z for the Zetas drug cartel - left with the bodies hanging from a bridge in Mexico. A clear warning to anyone denouncing their activities, even online. How ominous have the cartels of Mexico become? Is there any limit to their power or brutality?