At the time of the mass murder perpetrated by Norwegian Anders Behring Breivik last year I commented -- like others -- on the killer’s broken family background, in particular the absence of his father from the time he was one year old.

Recently another Norwegian, Aage Borchgrevink, has published a book which reveals another side to Breivik’s family experience -- the mental ill health of his mother, the Telegraph reports.

Psychologists reports going back to her son’s babyhood note that Wenche Behring is “a woman with an extremely difficult upbringing, borderline personality structure and an all-encompassing, if only partially visible, depression” and who “projects her primitive aggressive and sexual fantasies on to him”.

After Breivik's father Jens Breivik lost a child custody case with Ms Behring, social workers recommended that the boy nonetheless be removed from his mother to prevent "more severe psychopathology" from developing, a request that was ignored.

Borchgrevink said it was this that had convinced him that he was right to publish.

"I've given more weight to the public interest. The fact is that he was actually caught by the system before the action, not by the security police, but in his childhood. He was within the system, but the system let him go."

Last year I wrote:

The 32-year-old [Breivik] grew up in a Norway in which marriage rates were falling and divorce and cohabitation increasing. According to a recent OECD report on the wellbeing of families Norway is doing just fine regarding poverty and female employment, but it is one of the developed world’s leaders in out of wedlock births -- more than 50 per cent of children were born to parents without a marital commitment in 2007.

I wonder if one knew more about both parents this Norwegian tragedy would turn out to be, at bottom, a marriage tragedy.