This article analyzes historical sources devoted to the “Beria case”, in which it is suggested that the true version of the arrest and execution of L. P. Beria is far from the official one. They also give opinions that the so-called “Beria's letters from imprisonment” are fakes created to conceal the truth about extrajudicial reprisal against this prominent figure of the CPSU and the Soviet government. The study of the materials of the investigative case and historical and literary sources made it possible to formulate a hypothesis that these documents were written after the death of L. P. Beria alone by his regular speechwriter V. N. Merkulov or a group of authors, which included Merkulov, also a victim of repression. To carry out an authorship examination of Beria's letters to the CPSU Central Committee, a text attribution method was applied based on the measure Burrows's Delta with Eder's Delta and Cosine-Delta modifications, and Ward's clustering algorithms allowed visualization of solutions in the form o