Persuasion/WMG

Mr Elliot murdered his wife Fanny.
Mr Elliot is a sociopath, or near enough to one as we're going to find in a Jane Austen novel. Mrs Smith decries him as a Complete Monster, at any rate, and everything else we see is pretty consistent with that supposition. Given that, are we supposed to believe that he married wealthy young Fanny and then she conveniently died of natural causes, rendering him wealthy and free to pursue a marriage for greater social station?