The acting from Tennant was astonishing - I watched the follow-up documentary and there were films of Nilsen speaking - Tennant had got him off to a T.
Was he mad or bad? Who knows? Presumably he was a psychopath - he fulfils the criteria. Nobody seems to know what causes this in spite of much research.
I am not sure what the law is now, but I remember being shocked as a student to learn that psychopaths could not be sectioned under the mental health act (because psychopathy is not a treatable mental illness) and the only way to get them off the streets was if they were convicted of a crime. I am not sure what the law is now.
The majority of Israeli Jews do not want to occupy Gaza.