Carlos Bolsonaro, one of the sons of former Brazilian president Jair Bolsonaro, has been the target of police raids, reports say.
The raids have been carried out as part of an investigation into suspected illegal spying on political opponents during his father's term in office, according to Reuters.
Federal police served search warrants against Carlos on Monday, the news agency reported, citing two sources.
Carlos, a city councillor in Rio, was said to be his father's propaganda minister and ran an office inside the presidential palace suspected of putting out fake news against opponents.
The former leader's son has denied running a fake news operation.
But he is now being investigated for allegedly using data collected by the Brazilian Intelligence Agency - known as ABIN - through Israeli software called First Mile, which tracked the location of private mobile phones, a federal police source told Reuters.
The Supreme Court is also investigating the "fake" news outlet being run from inside the presidential office and which was dubbed the "cabinet of hatred".
A police statement said eight warrants were being served in Brasilia, Rio de Janeiro and two other cities to identify "the main recipients and beneficiaries of information illegally produced by ABIN through clandestine actions".
The operation was the closest that police probes have come to the far-right Mr Bolsonaro, who has been barred from running for office until 2030 for abuse of power and misuse of the media when president.
The wider investigation is looking at accusations of illegal monitoring of citizens by ABIN during Mr Bolsonaro's presidency between 2019 and 2022.
Supreme Court documents unsealed last week showed the spy agency is accused of illegal surveillance on at least three justices and a former Lower House speaker during Mr Bolsonaro's presidency.
Officers launched the probe on Thursday and, in a statement, revealed seven federal police officers were being investigated and had already been dismissed from their duties.
A total of 21 search and seizure measures were being carried out.
Police added the operation was being extended across a number of locations, including the capital Brasilia and Rio de Janeiro.
According to court records, the country's former intelligence chief, Alexandre Ramagem - a Bolsonaro loyalist planning to run for mayor of Rio de Janeiro and who has denied any wrongdoing - was among those targeted by the initial search warrants.
Police said the investigation centred on an "organised crime" group which operated within the intelligence agency.