The Court of Appeal reviewed the evidence at the trial, and the judge's directions to the jury, in some considerable detail - the judgment is available here: https://www.judiciary.uk/wp-content/uploads/2024/07/R-v-Letby-Final-Judgment-20240702.pdf
It's well worth reading as they looked at it all over three days, reviewed the transcripts of the trial, etc.
I'm not saying the Court of Appeal is perfect or beyond reproach, but it is the only analysis which takes account of all the evidence.
Curiously, the Defence didn't call a psychologist to analyse the notes, or give evidence as to how common these kinds of scribbled "confessions" are amongst the acutely unwell but innocent. Nor did they call evidence from the occupational therapist whose idea it was. Nor, for that matter, did they call evidence from statisticians, or from any other experts.
There are two possible explanations:
- It simply didn't occur to Letby or her team to do so. This would appear to be wrong as there was at least one expert who gave a report to the Defence but wasn't called to give evidence.
- They tried to obtain evidence, but either they couldn't find an appropriate expert, or they did find such experts, and their reports or preliminary findings were considered to be unhelpful.
We won't know, because Letby doesn't have to disclose her legal advice and her legal team can't do so without her permission. But, on the face of it, the second explanation would appear more likely than the former.
One expert who did write a report says he "doesn't know" why he wasn't called - he clearly thinks he might have been of use. But here's the thing. The expert probably won't be told the reason why he/she isn't called - for example if the legal team are worried that they will give interviews to the press later and waive the confidentiality of the explanation. An expert's duty is to assist the court, not one side or another. But the Defence aren't under a duty to call an expert purely because he or she might throw some light on the matter - so if the Defence have reason to think it might be unhelpful, they are not going to do so.