Monti, 42, and Bernardi, 51, were arrested for allegedly possessing and trying to selling a French-made Matra air-to-air missile, while Bergiolo, 60, was arrested for allegedly acting as an intermediary to sell weapons, a Turin police statement said.
The investigation relied on the help of an arms expert who contacted the suspects about purchasing the Matra missile on behalf of a third party, police said.
Throughout the course of the investigation, police used phone and data interception to view photos of the missile, which were exchanged via WhatsApp, they said.
The probe brought authorities to the home of Del Bergiolo, where an array of military-grade weapons and illegally held guns were found, according to police.
Del Bergiolo’s house allegedly also contained Nazi swastikas and references to the Nazi military Waffen-SS unit.
Investigations are ongoing to determine how the French-made Matra missile, which appeared to have once belonged to the Qatari armed forces, arrived in Italy.
The political party Forza Nuova has denied any current connection with Del Bergiolo.
“If one of the arrested was a candidate of Forza Nuova way back in 2001 (18 years ago!), we affirm that on the contrary none of the people involved have been militants of Forza Nuova – which has nothing to do with the search this morning,” a press officer for Forza Nuova told CNN.
Del Bergiolo’s lawyer, Fausto Moscatelli told CNN his client is a “weapons enthusiast.”
“My client is a collector and they sequestered weapons that were in his home. These weapons were not registered, but they were not connected to terrorism,” Moscatelli said.
“There was a misunderstanding with the Nazi paraphernalia, he also had fascist and USSR paraphernalia, but they (the police) only took things with swastikas,” he added.
Police said they found a cache of 26 guns, 20 bayonets, and 306 gun parts — including silencers and rifle scopes — along with more than 800 bullets.
CNN has contacted lawyer Monti and Bernardi’s lawyer Alberto Minasi della Rocca, who did not wish to comment for this article.