Picking up on one point in the OP, aren't a lot of serious offenders sentenced to life imprisonment, with some guideline on how long 'life' should mean?
It does not always mean until they die, but could be as little as 15-20 years, and if they show remorse and have treatment or whatever is necessary, may be released after that time, but on licence, as in they have to demonstrate they continue to not be a danger to society.
If they never show remorse or accept treatment, or they cause trouble in prison, they will not be considered for release until they do, like Charles Bronson or whatever he calls himself these days illustrates? Similarly, a life sentenced prisoner who has been released can be recalled to prison if he/she breaks the licence conditions.
I will not comment on whether CB is mad or bad, or whether he should be in prison or a secure mental health facility, but like PPs have commented, many very bad people are skilled manipulators, who will try and convince medical staff and the authorities that they are mad not bad, because they will be housed in a secure mental health facililty instead of a high security prison, which is often considered to be the less unpleasant option.
Like the Yorkshire Ripper, Peter Sutcliffe, who after years of being in a secure mental health facility has now been transferred to a standard prison.