From inquiries, the first trial by the judiciary led in 1979 to the condemnation of some exponents of the Brescian far-right. Then, acquittal came; a second branch of inquiry, raised in 1984 after revelations by some informers, put under  accusation other representatives of the subversive right; once again, the accused were acquitted in 1987 (first-degree) for lack of evidence and acquitted in appeal in 1989.
 
During all the inquiries and judicial trials pertaining to the massacre, the hypotheses of involvement by secret services and State apparata in the event constantly circulated. Firstly, the most resounding fact produced by the inquiries were the orders given by institutional players, which are still unknown today,  less than two hours after the massacre, in order to have a firemen squad cleaning with fire-engines the site of the explosion, wiping out proofs, evidence and traces of explosive before any magistrate or expert could do any survey or appraisal. Later, also the mysterious disappearance of evidence collected in the hospital from the bodies of the wounded and the dead raised suspicion, together with the last and recent anthrophological appraisal where the  presence of Maurizio Tramonte, an Ordine Nuovo militant and a collaborator of the late SID secret service was ascertained that day on the place through a photo.

During the third and last trial, on May 19, 2005, the Court of Cassation confirmed the request of arrest for Delfo Zorzi, now a non-extraditable Japanese citizen under the name of Hagen Roi, for his involvement in the Piazza della Loggia massacre. On May 15, 2008, six people were accused: three members and high-profile militants of Ordine Nuovo, a captain of the investigation squad of the Brescian Carabinieri and a collaborator of the then Interior Minister Paolo Emilio Taviani. On 21 October, 2010, after five and half days of reconstruction of the accusations, the public prosecutors in charge of the inquiry framed all the accused with the charge of partaking in a massacre – with the exception of Pino Rauti for who, instead, acquittal was requested for lack of evidence – still emphasizing his moral and political responsibility for the massacre.
 
On November 16, 2010, the Court of Assizes produced the first-degree verdict of the third trial, acquitting all the accused for lack of evidence. The branch of the inquiry was then modified many times through the years, once again never for a culprit to be found. After the last verdict the president of the Association of the families of the victims of the Piazza della Loggia massacre stated: “The trials for [political] massacres cannot enter a justice room anymore. I understand that the judicial thruth, a different one than historical thruth, is difficult to find but now it is not easy to trust institutions anymore”.