Four main cartels - in Tijuana, Sinaloa, Ciudad Juárez and the Gulf region - have fought each other since the late 1990s for control of drug trafficking along the US border. Some traffickers work independently of the main cartels, buying off politicians to get their way. Journalists in northern and coastal states are often the primary targets of gang reprisals.
Reporters Without Borders has recorded 40 murders of journalists and eight disappearances in Mexico since 2000. More than half of the victims were investigating drug trafficking. With two journalists killed and three disappeared in 2007, Mexico continues to be the western hemisphere’s deadliest country for the media. None of the organisers of these killings has been arrested or tried.