Interviewed by the Tsar

Paul Shaviv relates an anecdote about witnesses at the Barry Gourary library trial. Bloghead: The distaff side of the Chabad dynasty.
P. S. Did someone even see the picture of Reb Moshe�s (Alter Rebbe's son who allegedly converted) grave mentioned by Paul?

On page"Gimel" of Haskomas to Tanya it is signed by three Alter Rebbe�s sons; Dov Ber, Chaim Avrohom and Moshe. Little is known or talked about in regards to Moshe but everyone agrees that something did happen with him. Moshe Rosman writes in Founder of Hasidism: A Quest for the Historical Ba'Al Shem Tov. on Page 191:

There are various reports about Moses subsequent to the contest over the leadership of Habad, all indicating that he left the orbit of Hasidism and probably even of Judaism. In 1811, the Jewish Englightenment figure Isaac Ber Levinsohn related that he had learned from Hasidic informants that Moses had converted of his own free will and had been interviewed by the Tsar. In 1843, Bonaventura Mayer, a convert to Christianity, wrote that in the course of his travels in Russia he had met Moses serving as a Russian bureaucrat, something a nonconverted Jew would not have been able to do. According to Habad tradition, Moses caused much grief to his family but at the end of his life repented.

I heard that Moshe was versed in Russian culture and language (even before he left the fold) and he was instrumental in negations with the government during his fathers arrest, securing the ultimate release on YAT Kislev.