Board Thread:Dark Souls II/@comment-2.223.169.191-20140325204725/@comment-16047389-20140919150210

The whole isn't a theory. It is a fact that the strategy guide states that the lore of the Lost Sinner is that she is the Witch of Izalith. The how and why are ultimately left open to interpretation, but it isn't my "theory" that it is their claim.

If you have a problem with that idea, take it up with Future Press.

In any case, the points discussing this theory in general are listed through this article already. If you actually care enough to bring up some evidence or counter arguments to this idea, instead of just saying "you're wrong", then feel free. Until then though, your opinion doesn't concern me.