The tragedy of Taganrog in November, 1825 not only turned the last page in the history of Alexander I, but also gave incitement to the creation of legends about his transformation into mysterious Siberian elder (starets) Feodor Kuzmich. In people's mind, domestic pre-revolutionary, Soviet, émigré and foreign historical literature it was revived several times. In recent years, the legend was resurrected again by some modern authors who support the theory about the identity of Alexander I and Fyodor Kuzmich. This article is devoted to analysis of both classical memoir evidences and new sources of personal origin and official materials covering the last period of life, the circumstances of the illness and death of the Russian Emperor. The authors try to consider the history of occurrence of these materials, determine the accuracy and identify the causes of strengthening in the historical perception of the legendary versions of Alexander I resignation of power by dint of «phantom of death» in Taganrog.