I read about it years ago in one of those paper things with pages, back when computers were still mostly cumbersome things that very few people owned, and Al Gore was still working on the Internet. I think the book was called Memoirs of a Jewish Partisan, by Nahum Kohn, portions of the narrative originally published in Yiddish in a newspaper under the title Ich Hob Gevolt Leiben, and contains some harrowing first-hand details of the liquidation. I might be thinking of My Private War, Memoirs of a Jewish Partisan, but Amazon.com comes up blank for that title. This fact about Stalin is also repeatedly mentioned in Forged in Fury by Michael Elkins.
Thanks, I’ll look for it.