Later that day the paper says it received a “suspicious” afternoon phone call. “I am going to send my bodyguard to leave you a message,” the unidentified caller warned. Fifteen minutes later someone fired on a different El Norte office in the Monterrey metropolitan area with an AK-47, leaving bullet holes in windows and marks on the exterior walls. Next, according to the paper (which interviewed witnesses), “the criminal launched two 40-caliber grenades.” One exploded outside the building. The other went through a second-floor window into an occupied office but miraculously did not go off. Investigators collected seven shell casings from the AK-47.

Free speech in Mexico is under siege, columnist Mary O’Grady reports on Opinion Journal Live.

Nineteen days later, yet another El Norte office, this one in the upscale Monterrey neighborhood of San Pedro, suffered a third assault. This time three hooded assailants brandishing automatic rifles overwhelmed a security guard, doused the reception area with gasoline, and set it on fire.

So far no one has been injured in these attacks, but the paper says there has been no progress in the investigations and no arrests. (The Wall Street Journal has a business relationship with El Norte, which publishes The WSJ Americas five days a week.)

What is notable is the timing of the violence. On July 9, one day before the first terrorist attacks on its offices this summer, El Norte broke news involving an alleged link between the department of motor vehicles, known as the ICV, in the state of Nuevo León and stolen automobiles. The story said that 175,000 pairs of license plates had walked from the inventory of the ICV and that sources inside the ICV “said that many of these plates were used to legalize stolen cars or cars illegally imported from the U.S.”

If true, the paper was dangerously close to exposing a lucrative crime ring. The number of stolen cars in the state went up by 50% in 2011 over 2010, and a stolen license plate racket might be part of a larger modus operandi. According to El Norte, the difference between selling a stolen car in Mexico and selling it with a legal license plate is on average about 190,000 pesos ($14,000).

Five and a half years after Mexican President Felipe Calderón initiated an all-out war on the Mexican cartels that run drugs to American consumers, organized-crime rages in Mexico. But it is not limited to narcotics trafficking. Having made a bundle off prohibition, mastered the art of corrupting officials, and provoked a generalized breakdown in the rule of law, other gangster businesses are booming. When the press dares to expose their operations, it gets the El Norte treatment or worse. The paper has reported that 47 journalists have been murdered in Mexico since 2006, 13 have disappeared and there have been 40 attacks against media properties.

The Citizen Council for Public Safety and Criminal Justice (CCSPJP), a Mexico-based nongovernmental organization which tracks homicide statistics, found that five of the 10 deadliest cities in the world last year were in Mexico. The Council has also reported that of the 50 most dangerous cities in the world in 2011, 40 are in Latin America. Last year, for the first time, Monterrey joined that list as cartel violence spiked.

It is not a stretch to suggest that the attacks on El Norte, which is Mexico’s second largest newspaper, have to do with the paper’s investigative reporting on organized crime.

The state government initially said that it had identified the crooks (ICV employees) responsible for stealing the plates and that the ones they caught confessed to having sold them for scrap. If so, given the economics, it would make them some of the dumbest thieves ever. If the state’s story is true that they cut each plate in half by hand to make them salable to scrap dealers, they are also some of the most dexterous.

The state later announced that it was actually 313,000 pairs of plates that had gone missing. This time it said the thieves confessed to taking and selling 230,000 plates for scrap. That leaves 83,000 unaccounted for. El Norte has also interviewed two locals who say that they bought used cars after verifying the vehicle identification number with the ICV, only to be later informed by police that the cars were stolen. Both individuals were stripped of their cars and one of them says she had to pay a bribe of 100,000 pesos to avoid jail time. Requests for comment from the state went unanswered.

Of the many unintended consequences of the disastrous war on drugs, the destruction of institutions crucial to a free society may be the most pernicious. If the press is silenced it harms not only those who want to speak but also the wider public, which has a right to information. If El Norte cannot be protected, Mexico is in worse shape than commonly understood