Please don't rephrase or try to state what I think, LOL. Thank you.
Prisons have lots of mentally ill people in them. Some of them committed crimes, too.
I don't know whether Casey is the one who harmed Caylee or not. What I said is that I think she sounded delusional, illogical, and confused during her interviews with LE. She sounded dreamlike and seemed to be mixing up events past and present (i.e. thinking she was back in 2006 in some ways). Her affect was not appropriate to the situation. She also didn't offer any simple convenient lie or story to defend herself such as "a stranger took Caylee and told me if I told LE they would kill her". She made odd statements that didn't make sense. The detectives noticed how illogical her statements sounded and were checking out to be, that's why they asked her if she'd been committed at the mental hospital before.