Drug Wars in Mexico

This week the situation with the drug wars in Mexico really hit home with my family and friends.  A missionary that had been working in Mexico for close to 40 years was shot by drug cartel yesterday.  A truck approached them, and when they sped up the truck begin following them, and their truck was riddled with bullets, and one bullet struck the lady in the head.  My dad had stayed in this family's home when he was younger, and they were such nice people.  You just can't help but wonder why she of all people was attacked by them.  Her husband drove against traffic at approximately 120mph for around 70 miles.  I can't even imagine what he must have been going through while trying to drive her to medical help and safety.  I had never really given the whole situation in Mexico much thought, but now I am curious about the whole ordeal going on, and why it has gotten so out of hand.  I will post some links of some of the different stories just in case they are of interest to anyone.