It says much for poster's compassion and concern, but to me it raises another question. Why do we assume that when somebody like us acts in an unacceptable way, the rationale for which defeats us, we tend to assume that the person who committed the deed must have mental health problems?
What are we afraid of? That all of us, deep within us, has a capacity for evil that we do not want to be reminded of? A desire to place the evil-doer at arms length and say 'They are different from us, there mind is disordered' because it protects us from grappling with the nature of evil? What?
No evidence has been published that suggests this lady had mental health issues. Could the explanation for her behaviour be that she was an unpleasant person, who enjoyed the sense of power that trolling the McCanns gave her, knowing that while she lived a quiet and blameless life in her neat house in a nice village, she had the power to make other people's life a misery, yet nobody but her knew.
Some years ago I reported a gas leak. After investigation it was found that the cause was a leak in the main gas distribution pipe in the road. My house overlooked the junction of two major roads coming into Reading. One was already shut for roadworks. When the other one was partially closed because of the gas leak half of Reading was brought to a grinding halt for 5 or 6 hours. I stood at my bedroom window looking on the chaos and listening to local radio and thought:I caused all this with one phone call and only DH and I know this and the surge of power that ran through me, shook me with its intensity. I wonder whether it was this feeling of power, that nobody but she knew of whether was what this lady was enjoying. It is as reasonable a supposition as assuming she was mentally ill.