It took a third passage (and some very leading hints) before anyone at Readerville recognized the mystery author:

"Alix Bowen goes to see her murderer quite regularly. This will be her first visit for a month, her Christmas gift, her New Year's gift. Some of her friends disapprove of what could now, Alix realizes, be described as an obsession, but most of them are too polite to comment. Her husband Brian says nothing to deter her. He smiles indulgently, anxiously, as he listens to her stories. If he thinks her interest excessive, or unnatural (which it is, and he must), he does not say so.

"Alix's old friend Liz Headleand is less restrained. 'You're barmy, Alix,' Liz would comment, from time to time, over the phone, as Alix reports her murderer's latest intimations, her own most recent speculations. But then, Alix tells herself, Liz is probably jealous. Liz, a professional psychotherapist, probably thinks it quite wrong that an amateur meddler like Alix should have acquired such easy and privileged access to so notorious a criminal. Liz had missed her own chance to befriend the murderer. She, like Alix, had been in the same building with him, had been more or less held hostage by the police on his behalf: if Liz had thought quicker then, had acted quicker then, he could by now have been Liz's murderer, and Liz herself could be driving to visit him across this lonely moor."

Hint: this author has a more famous sister who was quoted here earlier this month.