Jack Culpepper’s “The Kremlin Executions of 1575 and the Enthronement of Simeon Bekbulatovich” (Slavic Review, September, 1965) notes a single anonymous chronicle dating to the early 17th century alluding to a mysterious Kremlin purge … several years after the notorious Oprichnina.
Regarding the other executions of the same year in Moscow on the square near the Uspensky Cathedral, the Tsar disgraced many individuals, ordering the execution within the Kremlin and in his presence, on the square near the Uspensky Cathedral, of the following: the boyar Prince Petr Kurakin, Protasii Iur’ev, the archbishop of Novgorod, the protopope of the Arkhangel’sky Cathedral, Ivan Buturlin, Nikita Borozdin, the archimandrite of the Chudov Monastery, and many others. Their heads were thrown before the residences of Prince Ivan Mstislavsky, the metropolitan, Ivan Sheremetev, Andrei Shchelkalov, and others.
According to Culpepper that Archbishop of Novgorod, Leonid by name, faced the executioner on October 20, 1575 after being summoned to a sobor — but no records preserve the conclave’s deliberations or the proceedings against Archbishop Leonid. Others both secular and ecclesiastical shared his fate throughout that autumn. (Ivan had no compunctions when it came to burdening his soul with the death of a clergyman.)
A Holy Roman Empire courtier who reached Moscow late that year would record by way of explanation for the bloodbath that the perennially paranoid Ivan had put to death some forty nobles for a suspected interest in his assassination.
This supposed plot against him is one possible reason for Ivan’s strange decision around the same time to faux-abdicate the throne. In September or October of 1575, Ivan plucked the ruler of a vestigial khanate dependency and made this gentleman, Simeon Bekbulatovich, Grand Prince of Rus’.
Ivan, of course, maintained the real power; he would claim to an English visitor that it was a ruse to throw off his murderers, telling him:
we highlye forsawe the varyable and dungerous estate of princes and that as well as the meanest they are subiect unto chaunge which caused us to suspect oure owne magnificence and that which nowe inded ys chaunced unto us for we have resyned the estate of our government which heathertoo hath bene so royally maynteyned into the hands of a straunger whoe is nothinge alyed unto us our lande or crowne. The occasion whereof is the perverse and evill dealinge of our subiects who mourmour and repine at us for gettinge loyaull obedience they practice againste our person. The which to prevent we have gyvene them over unto an other prince to governe them but have reserved in our custodye all the treasure of the lande withe sufficient trayne and place for their and our relyefe.
Ivan did indeed relieve his proxy tsar the very next year, demoting him to Prince of Tver and Torzhok. Despite the approaching “Time of Troubles” crisis following Ivan’s death when nobles would struggle for the right to sire the next Muscovite dynasty, the still-living former Grand Prince was such an absurd character that he never figured as a contender for the crown. (He would be forced into a monastery, however.) Bekbulatovich died naturally in 1616.