And even if she knew for a fact that Walter , not Oswald, Sickert drew the sketches, would they necessarily indicate that he harbored murderous desires towards women?

And finally finally finally...

Cornwell ignores the "Nemo" letter to the editors of the Times of London (the letter about Eastern criminal methods). Yet in a set up to a major rhetorical flourish, she does make a point of "Nemo" having been Sickert's stage name, only to instruct us that Sickert "dropped" this name "in the late summer of 1888 [and] he gave himself a new stage name that during his life would never be linked to him."

Oh, the certainty of it all. Oh, the manipulation of it all! Need I tell you what that new stage name is? No, you know it. It has been played out on the world stage for over a century now. It is synonymous with evil and murder and blood on the streets of London in the fog.

But Cornwell's flourish, no matter how effective rhetorically, still begs the question.
And Martha Tabram is still quite likely the victim of a different killer.