Were there witnesses of Anastasia Romanov's death?

No. and there was a curious government backed Media blackout ( obviously easier in the days when media was limited to wire services, radio and newspapers.) it is true her body was never recovered, and there were all sorts of confused signals. the Reds wanted all Romanovs dead or at least out of the picture, the Whites saw their Girl Czarina as a rallying cause, what could be more romantic than a young princess caught up in world-shaking turmoil. Indeed much can be said for both sides Anna Anderson and the argument that there were no survivors. (Anastasia) to the end of her days had a deep-seated fear of law enforcement officers of all kinds, being photographed by strange persons, and this seems natural enough- Basements. ( going to the basement of Blood) if her story is true, she clearly had help from IKGB ( czarist equivalent of KGB such as Dimitri) to make good her escape, and may have been given memory-altering drugs as well. the phobias were too deep seated to be accidental shocks from exploding shells at an ammunition plant, as some have suggested.