According to Rome prosecutor, Pietro Salvitti, quoted by La Repubblica, Guido Salvini was one of the targets of a "network" which aimed at slamdering various political opponents of Silvio Berlusconi via the Mitrokhin Commission, headed by senator Paolo Guzzanti, by claiming they worked for or were manipulated by the KGB, the former intelligence agency of the Soviet Union, dissolved in 1991. These targets included current Prime minister Romano Prodi, his staff, General Giuseppe Cucchi (current director of the Cesis), Milan prosecutor Armando Spataro, also in charge of the "Imam Rapito" case, as well as La Repubblica reporters Carlo Bonini and Giuseppe D'Avanzo, who discovered the Yellowcake forgery manipulations. This network includes, according to Salvitti, Mario Scaramella, Nicolò Pollari, head of SISMI intelligence agency indicted in the Imam Rapito affair, Marco Mancini, n°2 of SISMI arrested in July 2006 for the same reason, as well as Robert Lady, CIA station chief in Milan also indicted in the kidnapping of Abu Omar in Milan. .
Guido Salvini started investigating events relating to Italy's strategy of tension, which have involved a NATO stay-behind anti-communist network kwown as Gladio, in July 1988. After 463 interrogations, the investigations produced 60,000 pages. He indicted in 1998 David Carrett, officer of the US Navy, on charges of political and military espionage as well as participation in the 1969 Piazza Fontana bombing. He also indicted Sergio Minetto, Italian official member of Gladio, and pentito Carlo Digilio, indicted in the Piazza Fontana investigation. In 1995, Carlo Rocchi, the CIA's man in Milan, was discovered searching for information concerning Operation Gladio. According to Salvini's investigations, the neo-fascist organizations involved in the strategy of tension, "La Fenice, Avanguardia nazionale, Ordine nuovo" were the "troops" of "occult armed forces", directed by components of the "state apparatus related to the CIA." . The neofascists had decided to kill Mariano Rumor, on retaliation against his decision not to proclaim the state of emergency following the Piazza Fontana bombing — which, according to neo-fascist Vincenzo Vinciguerra, was one of the main objectives of this bombing. .