Rome's carabinieri police said Valter Lavitola, supposedly a friend of Ranucci, was the "alleged mastermind" behind the October 16 attack outside the journalist's home.

He is accused of having instructed a second man, Tavares Gomes Clesio, to recruit four men arrested in June who are accused of actually placing the bomb, police said.

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"Lavitola is suspected of having conceived the criminal plan, instructing Gomes to identify individuals capable of procuring the explosives and carrying out a demonstrative attack in front of the journalist's villa," they said.

Both men took part in an "initial exploratory inspection" outside Ranucci's home in September, police said, adding they were still looking for Gomes.

Detectives did not provide a motive for the attack.

Ranucci, the popular star of the weekly investigative show, "Report" on state broadcaster Rai, has described Lavitola as a "true friend".

Ranucci has taken on sensitive topics such as Italy's mafia and political corruption in past investigations, and has lived under police protection for years.

The journalist was not injured in the attack, which damaged two cars and part of his gate outside his home in Pomezia, south of Rome.

Details of the ongoing investigation are spotty, with local media reporting that Lavitola -- who has spent time in prison for corruption and extortion -- hoped to convince Ranucci to enter politics.

Lavitola, a former journalist and import-export businessman who owns a restaurant in Rome, is a well-known name in Italy, having been close to the former prime minister Berlusconi, who died in 2023.

In 2015, a lower court convicted Berlusconi for having bribed a senator, handing him a three-year sentence. The same sentence was given to Lavitola, whom prosecutors accused of having handed the cash to the lawmaker.