https://en.wikipedia.org/wiki/Vinnytsia_massacre https://en.wikipedia.org/wiki/Katyn_Commission

Accusations that the NKVD killed a bunch of Ukrainians and Poles for absolutely no reason other than “Stalin was evilly twirling his moustache”

Sources cited:

1. Nazi Germany
2. An “independent international commission” made up entirely of “experts” from Nazi-occupied Europe which were handpicked by the Nazi government, and agreed fully with initial Nazi “findings”
3. A bunch of other random sources citing the “independent commission”

Note how the Katyn Commission article goes out of its way to avoid the word “Nazi,” only saying “Germany” and “Reich”