Four people were arrested and 33 search warrants executed Thursday as part of the probe, Brazilian Federal Police said in a statement.

“On Thursday (8/2), the [Brazil] Federal Police launched Operation Tempus Veritatis to investigate the criminal organization that acted in an attempt to stage a coup d’état and abolish the Democratic Rule of Law, in order to gain political advantage by keeping the then President of the Republic in power,” the statement read.

A further 48 precautionary measures were also enforced, including a ban on contact with other people under investigation; a ban on leaving the country, with an order to surrender passports within 24 hours; and a ban on exercising public functions, said police.

Police have not named any of those under investigation, but Fabio Wajngarten, a lawyer representing Bolsonaro, confirmed that the former president is among their number in a post on X.

Bolsonaro will surrender his passport “in compliance with today’s decisions,” Wajngarten added.

Bolsonaro has not been arrested, nor has he been charged.

Two aides to former President Bolsonaro are among those arrested, reported CNN affiliate CNN Brasil, citing law enforcement sources. The arrests are also being widely reported in Brazilian media.

Several former ministers that served in his government are also being investigated, CNN Brasil reported.

The police declined to comment on Bolsonaro’s involvement or the arrests of his aides.

However the statement said that the investigation had uncovered evidence of coordinated efforts to build a narrative that fraud had been committed in the 2022 presidential election “in order to enable and legitimize a military intervention.”

One “axis” of these efforts was allegations that Brazil’s electronic voting system was vulnerable to manipulation, said police.

Bolsonaro frequently criticized Brazil’s electronic voting system, despite having been elected as a federal lawmaker five times and once as president in elections using that same system.

His criticism of the electronic voting system began before he was elected president, but reached a crescendo in the lead up to the 2022 election, which Bolsonaro lost to current President Luiz Inacio Lula da Silva.

A second part of the alleged plot involved attempts to plan a coup d’état involving military personnel, added police.

“The facts under investigation constitute, in theory, the crimes of criminal organization, violent abolition of the Democratic Rule of Law and coup d’état,” continues the statement.

President Lula said it was “very difficult” for him to comment on an ongoing police operation, but said that he hoped “no excesses were committed and that the full rigor of the law is applied” in a post on X.

In an interview with Brazilian radio station Itatiaia on Thursday Lula also said that he hoped Bolsonaro would be “afforded the presumption of innocence” that he hadn’t been afforded in the past.

This is a reference to Lula’s historic conviction on corruption charges, which was later thrown out.