A doctor has said that Abi is mentally ill and psychotic, so I don't want to say she's not as I know very little about her. But I do think that this was unusual behaviour from someone who is mentally ill... People who are mentally ill usually don't harm others, and in the rare cases when they do it's usually someone very close to them, eg the family that they live with. Or whoever happens to be there at the time, eg the greyhound bus guy. Going and seeking out a victim is very, very unusual IMO.
Which isn't to say that it never happens. I just don't want people thinking this kind of behaviour is typical of people with psychosis. There's enough stigma as it is. I also thought the crime sounded somewhat sadistic, and mental illnesses such as schizophrenia don't make people sadistic. When they do cause violence, it's usually because the person thinks they are protecting themselves, or because they think God told them to do it or something like that. So when I heard about this case, my first thought was that it was "Bunny Boiler" type behaviour, not mental illness, especially since it was reported that she'd recently been fired (which seems to have been untrue).
I'm sure sure what Abi's behaviour in court indicates, because she may already have been medicated. Antipsychotic drugs could certainly cause her to appear "out of it".
ETA it's also possible that Abi does have a mental illness, but wasn't psychotic at the time of the crime. But became psychotic due to the stress of being arrested. Bit like Luka Magnotta, who IMO does suffer from schizophrenia but wasn't psychotic at the time of his crimes.
It's also possible she has bipolar disorder, and a manic episode caused anger, impulsiveness and lowered inhibitions, but she was still aware that what she was doing was wrong. I can't think of any cases where psychosis caused someone to abduct and torture a child, but I will have to look it up. Or maybe Abi had a delusion that the baby was possessed or something like that? If so maybe she knew what she was doing and did it intentionally, but didn't know it was wrong.
All just MOO