PARIS— A panel of French judges placed former President Nicolas Sarkozy under formal investigation late Wednesday for allegedly accepting bribes and illegal campaign financing, and misappropriating Libyan public funds.

The decision came after years of allegations that Sarkozy relied on a multimillion euro donation from the government of Moammar Gaddafi to finance his successful 2007 presidential run.

The accusations that Sarkozy may have colluded with a foreign dictator to secure his own power amount to the gravest allegations levied against a former French head of state in decades. They also raise questions about the motives behind Sarkozy’s decision to spearhead a NATO operation against the Gaddafi regime in 2011.

The Wednesday night decision came at the end of a two-day period of questioning over an affair that Sarkozy has long dismissed as “grotesque.” Although the proceedings could still be dropped, the distinction of formal investigation means that French authorities now believe there is sufficient evidence that the former president might have committed a crime.

Sarkozy, 63, was released Wednesday night but placed under “judicial control.” Under French law, judges in each specific case decide the meaning of judicial review, but it normally entails travel restrictions and periodic check-ins with authorities.

In France, the judges who manage cases such as Sarkozy’s have broad investigative powers, and the decision issued Wednesday means that the judges in question will continue investigating the former president in the months to come.

But there is now a real chance that Sarkozy could stand trial.

The long-brewing affair began in 2012, when Mediapart, a French investigative media outlet, published a document from Libyan archives detailing the particulars of a transaction that amounted to 50 million euros in total ($68.5 million). If true, Sarkozy would have accepted more than twice what was then France’s legal limit for campaign funds, and would not have complied with transparency rules.

French authorities opened a general investigation into the Libya case the following year, but Sarkozy was summoned by authorities for the first time only on Tuesday.

The allegations have been a constant presence in French public life since they first came to light in 2012. In the years since, the case has seen a number of unexpected twists and turns that have often resembled the plot of a political thriller, including illicit meetings between government figures and prominent arms dealers and businessmen.

In November 2016, for instance, Ziad Takieddine, a Franco-Lebanese millionaire arms dealer, told Mediapart that he had personally overseen the cash transfer of 5 million euros ($6.3 million) of Libyan funds in three suitcases delivered to Sarkozy’s chief of staff between 2006 and 2007.

As recently as January, Alexandre Djouhri, a French businessman, was arrested in London in connection with the ongoing investigation. Djouhri is currently fighting extradition to France.

Sarkozy is already slated to stand trial in another case concerning allegations of campaign finance abuse during his second unsuccessful presidential run in 2012.

The former conservative president has also weathered similar scandals in the past, such as the so-called “Bettencourt Affair,” when he was accused of manipulating Liliane Bettencourt, an elderly billionaire heiress, into funding his first campaign.

The charges in that case were dropped in 2013.

But the Libya scandal could prove to be different, given the potential connections the case may have to a military operation against the same government with whom the sitting president may have had a conflict of interest. There is also the question of civilian casualties incurred in Libya during the NATO strike.

On Wednesday night, Takieddine spoke on BFM-TV, an appearance during which he reiterated his earlier claims. “He’s a real liar,” he said of Sarkozy. “You will see.”

Read more