It isn’t true at all that those who know LL are sure she did it. Her colleagues, friends and family are adamant that she did not.
I have no idea what behaviour was deemed ‘chilling’, but I think things got to a stage with her where literally anything was reported upon as having a sinister twist. She had a diary with a cartoon dog on it; she held her cat before she was arrested; oh my god, she had a picture on her wall which said something about sparkles, clearly a disturbed woman 
Anti depressants, especially very strong ones, and sleeping tablets combined make you feel numb. They manage feelings of depression and anxiety by dulling these feelings but also dull other feelings and can make the person appear flat and disassociated from everything. Combined with sleeping tablets which can make you disoriented and woozy even the next day,
But tbh I don’t like this focus on her character because her personality and whether we like her or not is not on trial. To give another example, I think there is a good chance another shocking miscarriage of justice happened with Michael Stone, who was convicted of attacking and killing Lyn and Megan Russell in Kent in the 1990s and attempting to murder Josie Russell. It was a really horrific crime and I remember how high profile it was at the time. Michael Stone was convicted in 1997 (I think) and has insisted on his innocence ever since. I can’t say whether he’s innocent or not but I can say I believe there’s enough there for reasonable doubt.
That does not mean I think he’s a good guy or that I want to go for a drink with him or that I believe he is a pure and honest soul. By all accounts he was prone to aggressive outbursts, was violent and unpredictable and had already been convicted of armed robbery and assault. None of that means we should say ‘well, we don’t like him so he should just stay in prison.’
None of the above applies to LL, but her personality is not on trial or relevant unless you want to befriend her. She could be the coldest, dismissive, rudest nurse there is and it still doesn’t mean our judicial system gets to convict her of crimes that have not happened.