Hi Humdinger
It caught my attention because it was a qualifier, it wasn't an emphatic 'I believe' or 'He is'. We say things in the heat of the moment which can be telling or at least, interesting. Many of us believe OW knows the truth and so something like this stands out.
For me it sounded more like ... I still, after all of this quite compelling and damning evidence, which the Magistrate believes is sufficient to warrant a trial for Allison's murder, believe he is innocent. She sounded deflated, as if she herself was having difficulty 'believing'. Sort of like a Freudian slip, giving away more than she was actually saying or perhaps, the opposite of what she was saying.
Anyway, that's my take, would be interested as to what everyone else thinks.