All of this is based on my opinions but many in Mexico feel like I do:

Los Zetas are the new guys in Mexico and they broke all of the Mexico's underworld rules since day 1; and brought level of violence never seen in Mexico. They introduced the beheadings, body dismemberment, extortion, kidnappings for ransom and more than anything fear and levels of insecurity never experienced by Mexican citizens. They are so feared; kidnapping groups, extortion groups and other non affiliated cartel criminal groups call themselves "Los Zetas" or being part of the "Los Zetas", these groups are known as "Zeta piratas" or "Fake Zetas" in Mexican law enforcement. Note there has always been kidnapping groups in Mexico but many if not all had nothing to do with drug trafficking or the main cartels in Mexico. There is no other group that is as ruthless than the Los Zetas, every major catastrophe in Mexico has been perpetrated by this criminal organization. Many of the beheading, dismemberment etc. has been perpetrated by Los Zetas and as long as they operate they are going a lot of violence and war on the streets. There can be and is truce between the other cartels except Los Zetas and their allies that are with them for survival.

http://www.amw.com/fugitives/case.cfm?id=76152

here is a link of a guy that is part of the Los Zetas dosen't mention, but you can just tell about him he is cartel affiliated he is wanted for murdering his ex-girlfriend outside of a mexican restaurant

The first Zetas female leader?

http://latino.foxnews.com/latino/news/20...test=latestnews

Y do cartels make it a point to kill innocent people

It's mainly Los Zetas but the overall murder of innocent civilians is a drop of water compared to the 42,000 killed, most if it is criminals killing criminals but Mexican soldiers have killed quite a bunch of cartel members also.