Arturo Fernandez Lopez, a midlevel accountant in a division of Mexico's Interior Ministry, got a lump in his stomach two years ago as he was crunching numbers. The 55-year-old bureaucrat began to notice what he calls "irregularities" in the office accounts--overly expensive purchases and what appeared to be evidence of no-bid contracts. Disaster-relief material and money destined for the coasts had somehow wound up in Mexico's interior without sufficient explanation. On July 2, 2002, Fernandez presented an official complaint to his office comptroller. But 17 days later, when he showed up for work, armed policemen outside the office stopped him at the door. "The police told me they had an order from my boss not to let me in," says Fernandez. Not long after, his paychecks simply stopped arriving.

But the accountant would persevere and help uncover what may be a massive scandal. Shortly after being fired, Fernandez sought help from the Federal Institute for Access to Information (IFAI), an agency started to help ordinary citizens obtain information from the government through a new transparency law. President Vicente Fox was swept into power four years ago partly on his opposition PAN party's promise to transform the corrupt system of patronage and secrecy that defined the 70-year reign of the PRI. Graft and bribery continue to plague Mexico, but the new transparency law--passed by the Congress a year and a half ago and modeled in part on the U.S. Freedom of Information Act--is shedding some much-needed light on the many dark corners of the system.

Already, more than 45,000 Mexicans have filed official requests through the IFAI. They range from the mundane (how many people there are in the Army) to the very complex (the details of the rescue of Mexico's banking sector in the mid-1990s). All show a public hunger for information that belies the oft-repeated mantra that Mexicans, as a people, are apathetic about issues like accountability and reform. Mexican institutions like the state- controlled oil company, Pemex, and Mexico's Social Security Institute have begun to disclose more information, and in a timelier fashion, than ever before. In May the IFAI prevailed on the government to explain why it had kicked two Cuban diplomats out of the country, following the first serious row between the two nations in years. The Fox administration had said little about the spat, but after repeated IFAI requests were made, the government released a 32-page document detailing what it claimed was Cuban meddling in Mexico's internal affairs. The government says that the Cuban diplomats were working with leftist political parties, including the PRD, to undermine the administration.

Fernandez was one of the first people to use the IFAI database. He asked for documents that he believed would support his claim that there had been improprieties in the management of a disaster-relief fund, which was in turn part of a larger government superfund called FONDEN. Officials at FONDEN oversee smaller trust funds which have historically been more vulnerable to corruption in Mexico because of a 1993 law that removes them from the same kind of public scrutiny reserved for normal government-administered funds. According to Samuel del Villar, a Harvard-educated anticorruption activist and scholar who has authored several constitutional reforms, the growing prominence of trust funds has led to what he calls Mexico's "dictatorship of corruption." The extent of institutionalized corruption reaches into the hundreds of millions of dollars, he claims. "It's absolutely unconstitutional to say that those funds are not subject to the same kind of public and legislative scrutiny, just because they are trust funds," says del Villar. "This shows the extent to which the whole system has been disfigured."

According to Maria Marvan, the director of IFAI, the government's first response to the Fernandez request was to say that it didn't have the relevant documents. "So we reviewed what their obligations were and said, 'Well, it's a pity because you are mandated by law to have the information'." Within a few weeks, Fernandez had the documentation for 2001 and 2002, and several months later, at the IFAI's insistence, he would get the papers for 2003. An internal auditing board from his old office subsequently agreed to pursue an investigation, and by July, Fernandez had tallied up more than $30 million in irregularities. Curiously, the internal auditor was fired not long after he authorized the investigation.

But the case was beginning to attract press attention. A journalist at the Mexican paper La Cronica wrote several stories about it. Then, last spring, two separate investigations were begun, one by a senator and another by a group of PRI congressmen. The Mexican attorney general's office has also apparently opened up its own separate inquiry--and nearly two years after Fernandez made his first official complaint, the government finally came round. Interior Minister Santiago Creel told the Mexican newspaper Reforma that investigations had identified eight suspects who were the objects of penal inquiries, though he did not mention any names.

Unsurprisingly, an establishment backlash against the new law has begun. The Mexican Congress, at the behest of two PRI senators, is currently debating a new "national security" bill that would make it more difficult for the public to gain access to government files. If passed, the law would give the executive branch total control of which information could be made public, and give national-security considerations ultimate priority in disclosure decisions. It would also extend the embargo period for certain documents from 12 to 30 years. Mexico's financial sector, in particular, has lobbied hard for more restrictions on information, fearful that full disclosure could disrupt Mexico's economy. "We are inside a very interesting fight," says Marvan. "They have become much, much better at looking for legal arguments to [withhold] information, and we have become better at looking for arguments to free the information."

Fernandez has paid a price for his courage. In October 2003, while leaving his house in Mexico City to take his daughter to school, assailants shot him four times through the window of his car, including once in the face. He was nearly killed in the attack. No charges have been filed, and the investigation is ongoing. These days, he doesn't leave the house without an armed bodyguard. "Of course I'm scared," he says, "but I can't stop now." The bigger question is whether Mexico can overcome its own fears about cracking open a government too long shrouded in secrecy. The transparency law is a big step forward--and if it doesn't get weakened, Mexico will be much the better for it.