The first document accusing hetman Ivan Mazepa of betrayal and secret negotiations with Poland was submitted by Kochubey to Moscow in August 1707 from Baturyn through Nykanor, a monk of the Sevsk Savior Monastery, who was interrogated in Preobrazhensky Prikaz, but at that time the case was suspended.

In January 1708, in Moscow he presented the main points of the denunciation to Tsarevich Aleksei, and accused Hetman Mazepa of having relations with Polish King Stanislaw Leszczynski and attempts to arrest Peter I.

On 17 February 1708 the denunciation, written from the words of Kochubey and his relative Ivan Iskra was sent to Moscow by Okhtyrka Colonel Fedor Osypov with the help of his clerk V. Kobeliatskyi.

On March 1, 1708, Peter I wrote about the crime of Kochubey and Iskra to his bedchamber count Golovkin and secret secretary Shafirov, who were investigating the denunciation materials by his order.

[7] After the transition of Ivan Mazepa to the side of the Swedes, Kochubey was celebrated as a martyr for the truth and a hero in the Russian Empire.