The case was very complex and the trial lasted many months
Detectives pieced together shift patterns, mortality rates at the hospital etc. to “catch” her.
However she is maintaining her innocence.
It does make you think.
Criminals can convince themsslves they are not guilty.
Regular people can do it as well. Narcissists are great at blame shifting and gaslighting and guilt shaming. Perpetual victims (everyone is against me types) are great at it. Karens are great at it.