A general view in Mexico Photo: VCG

On August 4, 2020, a fire at the Beirut port ignited one of the largest non-nuclear explosions in history. It disfigured the city, took more than 200 lives and shattered Lebanon's psyche.

The blast was felt as far away as Cyprus, and the destruction is hard to fathom. But if one thing can outweigh what happened to Lebanon that day, it is what hasn't happened since.

Not one culprit has been put on trial, jailed or even identified. Families of the victims have received no visit, apology or explanation from those at the top.

Mexicans vote Sunday in a national referendum promoted by President Andres Manuel Lopez Obrador on whether to investigate and prosecute his predecessors for alleged corruption.

Lopez Obrador, a self-styled anti-graft crusader, says the public consultation will strengthen participatory democracy, but critics see it as little more than a political stunt. To be binding, 37.4 million people - 40 percent of the electoral roll - must participate, but many voters appear unenthusiastic.

While the "yes" vote could win up to 90 percent, it will be difficult to achieve even 30 percent turnout, said Roy Campos, director of the polling company Mitofsky.

Rosario Gomez is among those who plan to vote at one of 57,000 ballot boxes set up by the electoral institute, compared with more than 160,000 for June's legislative and local elections.

"It's about time these thieves pay!" the 52-year-old market vendor said.

Mexico is ranked 124th out of 179 on Transparency International's world corruption perceptions index.

But former presidents can be tried like any other citizen and critics argue that the referendum is unnecessary.

"Waiting for the results of a consultation is making justice a political circus," said Jose Miguel Vivanco, regional director of New York-based Human Rights Watch. 

Former National Electoral Institute president Luis Carlos Ugalde argued that if the prosecution has evidence against the ex-presidents, it's not necessary for "the people to tell you yes or no."

Although the vote was Lopez Obrador's brainchild, he has ruled out voting himself because he does not want "corrupt and hypocritical conservatism" to accuse him of vindictiveness.

The referendum question proposed by Lopez Obrador named five predecessors - Carlos Salinas, Ernesto Zedillo, Vicente Fox, Felipe Calderon, and Enrique Pena Nieto, whose terms in power stretched from 1988 to 2018.

Lopez Obrador has accused them of presiding over "excessive concentration of wealth, monumental losses to the treasury, privatization of public property, and widespread corruption," drawing angry denials.