The violence against women journalists is just one more addition to the violence against women in general that has rocked Mexico in recent years and sees no sign of abating. It is also worth noting that it isn't only the cartels that are targeting women, and it isn't only against women that violence is taking place. The State is a prime actor in the overall game as well.
All that said, the cartels have taken a new tact by literally tracking twitter, facebook, and other other on line sources to see who is reading or writing what and then taking action to shut up the writers, and scare off the readers. The tactic is not without success either. For example, almost no newspapers in Mexico reported any of this. The State hasn't done anything to take this on either. My guess is that the State sort of likes the idea.
So expect this crap to continue.
The following is from the Women News Network.