AlexP, this is shocking! Are you referring to the tombs in the grand ducal vault alone, or also the tombs in the Cathedral? I thought it was a MAJOR excercise to open up the tombs...
Pers, I am sorry that is shocking, dear friend, but yes, they were all desecrated, all of them, to the last, please see Belochka's post below. Again, all of us in the Emigration knew this, and my grandmother (my grandfather and my grandmother's three sisters had already been liquidated by that time, as well as my aunt) vividedly remember the parading-around of these dug-up skeletons, some of strung up lamppost style. It went for two-or-three months. And yes, they dug and blasted...why do you think that the Krepost was off limits for nearly 80 years and that it is in such a dilapidated state? Shocking beyond shocking. But they did the same thing in France nearly 130 years before. Something disgusting about it.
I believe Belochka is correct. The burial vaults are there but it is anyone's best guest if (a) any person is really buried there and (b) if there is a person that is buried there, whether or not it is indeed the person named on the tomb.
Nearly everyone doubts it. Everyone then, everyone know. And this was done in the name of the people...vox populii.