This article explores the history of one of the investigations of the Red Terror period into the “Reserve Rightwing Trotskyite Center of the Counterrevolutionary Nationalist Organization” (1938-56) in Azerbaijan. More than 300 people were convicted in this case, including members of the senior leadership of the Azerbaijan SSR and deputies of the Supreme Soviet of the USSR. Therefore, this case was one of the largest cases of that period. However, it was subsequently proved that the case was fabricated, and all convicts were rehabilitated. In connection with the sequential presentation of events, a narrative method of investigation was used in the article. The scientific novelty of the work is that this research is conducted for the first time. The main conclusion is that this political case was fabricated from the very beginning, and the investigation was conducted by illegal methods. In the work on the article, archival materials, as well as studies by other authors on the theme of the Red Terror in Azerbaijan were studied.