Quoting Daniel Hedinger’s A Global Conspiracy? The Berlin - Tokyo - Rome Axis on Trial and its Impact on the Historiography of the Second world War:

The […] question of Italy’s war guilt proved too ambiguous to bring before the courts. This is not to say that there was no reckoning with Italian fascists at the end of the war. It was in Italy where the drumhead court-martial justice advocated by Churchill [in 1943] was widely used. By mid-1945, an estimated 10,000 fascists had been killed without being tried in court. In addition, by the end of 1947, ten thousand trials had been conducted in local jury courts in which thousands of convictions and hundreds of death sentences were handed down. But amid the chaos of the early post-war period, it was not possible to discern any coordinated procedure. Given Italy’s double role between 1943 and 1945 as both victim and perpetrator, no real interest existed on the part of the Allies or the Italians to have the history of fascism or that of the German-Italian cooperation scrutinised in court. So, even though the possibility of a major tribunal did indeed exist at least until April 1946, in the end there was never to be an ‘Italian Nuremberg’.

(Emphasis added.)