French investigators in 2016 zeroed in on properties owned by Omar Bongo's family in France.
They suspected several of his relatives knowingly benefitted from a fraudulently acquired real-estate empire worth at least 85 million euros ($87 million).
Ten of Omar Bongo's 54 children have been charged with allegedly concealing the misappropriation of public funds, a Paris-based legal source told AFP.
As a sitting head of state, Ali Bongo had immunity.
The empire includes property in Paris and the Mediterranean resort of Nice, alongside a fleet of luxury cars.
An investigating judge last year determined that much of the money came from "undue commissions" paid by French energy giant Elf, now a part of TotalEnergies.
Omar Bongo's children also have properties in Britain and the United States, bequeathed or acquired after his death.
Nostalgia for life under the elder Bongo remains strong among a small number of Gabonese who hark back to when at least some oil revenues trickled down.
But that has since dried up.
His son enjoyed no such boon as oil revenue fell from 2014, experts and coup leaders say, noting Bongo was surrounded by "traitors" and "profiteers" while locked in an "ivory tower".
Source: AFP
