To Princess Luna, Princess of the Night.
Princess I’m glad you came to me with this rather than causing a ruckus about it, if we are indeed dealing with a conspiracy here that could’ve been disastrous both for your own personal safety and for any chance of seeing the truth uncovered.
But regardless my analysis of the document that disbanded the Night Guard has shown tampering, though I am afraid not in the manner you were undoubtedly hoping for; it would appear that the signature of Princess Celestia is indeed genuine and would appear to have been made with full knowledge of what she was signing.
What is interesting is the signature of Princess Cadence; while it is indeed her signature on this document, that much I can indeed confirm, it would appear that the main body of text that makes up the document was modified at some point after she signed the paper. This to me would suggest that Princess Cadence in fact signed this document without knowing what it would ultimately be used for.
You said that the arrest warrant the guards have been acting on was for your investigator? Why in Equestria would Princess Celestia order that, it doesn’t make any sense to try and arrest somepony for trying to look into a disappearance.
I think you, me and your investigator need to meet face to face sooner rather than later.
Sincerely
Doctor Chronos.