Was Charlotte Armstrong a witch?

[lostintwilight]

From the back of "The Case of the Weird Sisters":

Anthony Boucher calls Charlotte Armstrong "one of the few authentic spell-casting witches of modern times." Never before available in paperbacks, this novel bears further witness to her mystery-writing witchcraft.

[RareMale]

I don't think Boucher meant that to be taken literally, but it is a bit over the top for a book review.