KSM is locked up in Guantanamo Bay, and is undergoing some kind of legal proceedings. He wrote a manifesto, "Statement to the Crusaders of the Military Commissions in Guantanamo” in October, addressing a copy to each member of the military court. The military judge overseeing the process ruled a month ago that stuff written by the high value detainees, like KSM, could no longer be kept classified. That free'd the way to the Huffington Post obtaining a copy of the manifesto, and publishing it as a news item.
He's preparing two new manifesto's, one will cover why the Mujahedeen carried out 9/11 and whether it was a terrorist operation or an act of self-defense,” and a final chapter will delve into "the truth about the so-called ‘War on Terror’."
I have long maintained that our government has completely lied to us about this stuff. But I wouldn't take KSM's writing as entirely accurate either.
HuffPo has a long write-up - http://www.huffingtonpost.com/2014/01/14/khalid-sheikh-mohammed-manifesto_n_4591298.html
And they have published the manifesto here:- http://data.huffingtonpost.com/documents/1004897-khalid-sheikh-mohammads-statement