In a country where former presidents have long lived out their days in the comfort of impunity and vast wealth, Luis Echeverría made history this week when he went before a special prosecutor to answer to charges he had played a major role in two student massacres.
Though few expect that the 80-year-old president, who ruled Mexico from 1970-76, will be convicted or face jail time, historians and activists alike hailed his appearance before a prosecutor as groundbreaking.
After Chile's prosecution of former ex-dictator Augusto Pinochet and Peru's Truth and Reconciliation Commission investigating the two sides of a war in the 1980s-90s, Mexico is the latest country to crack the files open on once untouchable leaders.
"That there is a direct move against a president is unprecedented," says George Grayson, a professor of comparative politics and Latin America at the College of William and Mary.
During the 71 years that the all-powerful Institutional Revolutionary Party, or PRI, ruled Mexico, most ex-officials remained untouchable, says Mr. Grayson.
Former presidents Plutarco Elias Calles and Carlos Salinas simply went into voluntary exile when they ran into trouble with subsequent administrations.
"I never dreamed I would watch President Echeverría going to testify," says David Roura, an activist who was jailed twice during the early 1970s for his role in leftist student groups. "Even 30 years later, it feels good to see it."
Despite the euphoria, analysts say Mexico has a long road ahead if it hopes to bring justice for past wrongs. Other campaigns in Latin America to investigate and prosecute political crime have not landed a single senior leader in jail.
Echeverría's visit to the special prosecutor in Mexico City, for example, came the day after the Supreme Court in Chile finally halted the lengthy prosecution of Mr. Pinochet for dozens of political killings during his rule. The court found him in failing health and unfit to stand trial.
A truth commission established in Argentina to examine the disappearances of some 30,000 people during the so-called "Dirty War" let top generals in the ruling junta walk free. And to date, no ranking military officer has been convicted of abuses during Guatemala's 36-year civil war, though investigations have implicated the military in more than 90 percent of the cases.
Echeverría's testimony may mark "an important advance symbolically," says José Antonio Crespo, a Mexican scholar who has written two books on the PRI.
"But we'll see if it pans out legally."
The statue of limitations has run out on most of the crimes that Echeverría is accused of committing.
Raul Alvarez, a former political prisoner who filed one of the complaints against him, says even if this process doesn't lead to criminal charges, the former president's testimony may help consolidate cases against a network of PRI officials who shifted between senior government positions during Mexico's bloody 1960s and 70s.
EcheverrÍa was questioned Tuesday on two specific events: the Oct. 2, 1968, massacre of student protesters in Mexico City's Tlatelolco plaza, at which time he was interior secretary, and the slaying of 30 students during a 1971 protest march, at which time he was president.
On the advice of his lawyers, Echeverría did not respond immediately to nearly six hours of complaints listed by special prosecutor Ignacio Carrillo. He has 30 days to reply in writing.
A flood of similar cases is expected in the coming months, now that Mexicans have access to millions of previously sealed government records and files.
President Vicente Fox, whose 2000 election victory brought down the PRI, opened the files to the public last month. He appointed special prosecutor Carrillo to follow up a study by the National Human Rights Commission, which confirmed that at least 275 people disappeared in the 1970s and early 1980s.
Fox is in a tricky position with regards to Mexico's troubled past, analysts say.
On the one hand he promised to bring a climate of clean government, widespread justice, and an end to decades of political impunity.
But he also has locked horns repeatedly with a hostile Congress still controlled by the PRI, and has so far failed to push through key reforms he promised when he deposed the party.
Echeverría's session with Carrillo, ironically, came the same day Fox was celebrating the second anniversary of his historic election victory, prompting speculation he's bowing to pressure to show concrete action.
There are also concerns such moves could backfire.
"Let's say Fox gets Echeverría into court and he convicts him. What does he gain?" says Grayson. "The continued hostility of the PRI and nothing passed through Congress.
"If Fox is perceived as picking on an old guy in their party, it will make his job that much harder."
It's a gamble the kind that has made the cowboy boot-wearing Fox famous.
Such high-profile cases could also win back the hearts and minds of the Mexican people, if they perceive that long-neglected wrongs are at last being officially addressed.
"For years, these were nothing more than stories written about in newspapers," says Raul Alvarez, a member of Committee of 68, which filed the complaints against Echeverría. "Now, finally, they are cases being talked about in court."