Mexican President Andrés Manuel López Obrador said Monday that his predecessors could still face prosecution despite low turnout in a referendum on whether to investigate them for alleged corruption.
With more than 99 percent of ballots counted, 97.7 percent of voters supported a probe, compared with 1.5 percent who were against, the National Electoral Institute (INE) said.
But turnout was little more than seven percent – far from the 40 percent necessary for it to be binding, it said.
"This does not rule out the possibility of trials," said López Obrador, who had championed Sunday's referendum.
"The authority has the right at all time to act when it comes to judicial matters as long as there is evidence," he told reporters, describing voter participation as "a triumph."
In Mexico former presidents can be tried like any other citizen, and critics argued that the referendum was unnecessary.
The former presidents targeted by López Obrador are Carlos Salinas, Ernesto Zedillo, Vicente Fox, Felipe Calderón and Enrique Peña Nieto, whose terms in power stretched from 1988 to 2018.
None of them is known to be under investigation.
López Obrador said that "the important thing is that a democratic process was started so that no one feels untouchable."
The vote was "a good start" for another referendum he plans for March on whether he should continue as president or resign from office before his term ends in 2024, López Obrador added.
The INE set up around 57,000 ballot boxes, compared with more than 160,000 for June's legislative and local elections, and carried out limited promotion activities citing a lack of resources.
López Obrador has repeatedly criticised the poll body, which rejected his accusations that it did not fully support the referendum.
"It's not a matter of budget. It's a matter of will," the leftist president said.
"They were not enthusiastic about this consultation and they have not been enthusiastic about democracy," he added.