If you delve around in anyone's psyche there will be dark thoughts, the Pollyanna archetype / Mary Poppins type is a bit of a myth and can often mask suppressed and potentially sinister traits. Self awareness and examining / exploring those thoughts can help to change damaging behaviour patterns. Most people will self harm before they directly harm others, hence eating disorders, cutting, addiction. Very few serial killers had zero red flags prior to capture. Being "cold" or anxious means little in isolation, and certainly doesn't immediately point to the likelihood of harming others.
Part of those damned post it notes and other scribblings shows that one of the more damning sentences could be prefaced "They said" but it's so chaotic it's difficult to fully interpret.
I struggle with paranoia and intrusive thoughts at varying levels depending on stress in my life. Sometimes really awful thoughts go through my head and it horrifies me. I then remind myself that in my 50+ years of life I have consumed a vast amount of true crime, fiction, been exposed to all sorts of media and sensationalisef news material. That all contributes to the brains reference points for processing emotion and influencing thought processes, it's not that I am intrinsically evil, although self blame and shame are also part of my make up, ironically because I was falsely accused of harming my DC as an infant.
Which of course will be jumped on by some as evidence of personal bias with regards to my interest in this case.
But what can I say? We as a species are complex creatures, and understanding of our brains and psychology are still largely in infancy.
The fact remains that the medical evidence is in serious dispute. Until that is resolved, analysis of motive / character is a moot point.