After reading the Wikipedia page on the Troubles period of Russia, and the transition into the Romanov dynasty, I noticed all associated pages that mention the False Dmitry convey an absolute certainty that they were actually false. I am not claiming or hoping they weren't, but I got curious as to based on what exactly were people really sure? Thanks in advance for any pointers. I just found this period of time so fascinating due to its shifting inner and foreign policies in Russia during this time, as well as of course, those strange characters that were the False Dmitrys.
Because while there was doubt as to just how Real Dmitrii died, there was no denying that he was dead. More can always be said on the matter, so if anyone else would like to dig into the Time of Troubles, please don't let this post stop you! (Especially as to whether the 'False' label was a period application - I definitely second that question.) For the meantime, OP, on the matter of the Dmitriis being False, here's u/mikedash examining the circumstances around and the inquiry into the death of Dmitrii Ivanovich.
Oh, and another associated question if I may. Did anyone at the time refer to them seriously as False Dmitry, or Pseudo-Dmitry?