Jens Breivik, the father of jailed Norwegian mass murderer Anders Breivik, has written a book expressing feelings of guilt and responsibility over his son’s actions.

Anders Behring Breivik admitted killing 77 people when he bombed central Oslo and then went on a shooting spree at a youth camp on nearby Utoeya island in 2011.

His parents separated when Anders was a year old and Jens Breivik claims to have had little contact with his son.

Entitled My Fault? A Father’s Story, the book is set for release in October.

“I feel some guilt and I feel some responsibility. What would have happened if I had been a better father? Would Anders have done what he did?” Jens Breivik wrote, according to an excerpt of the book released by the publisher Juritzen.

A retired Norwegian diplomat living in southern France, Jens Breivik wrote the book with the help of a ghost writer and is expected to question his behavior as a parent and his role in the life of the radical far-right killer.

Jens Breivik has written a book expressing feelings of guilt and responsibility over son Anders’ actions

In 2012, Anders Breivik was sentenced to the maximum 21 years in prison for carrying out the country’s worst peacetime massacre in its modern history.

Anders Breivk harbored extremist right-wing views and claimed he had reacted against what he saw as a Marxist-Islamic takeover of Europe.

His deadly rampage against a Labor Party youth camp on Utoeya island was found by an Oslo court to have been a premeditated act of terrorism.

Anders Breivik’s jail term can be extended if he is deemed to remain a danger to society.

Jens Breivik has often been described as an absent father after the separation from his wife. At the time of the separation, Jens Breivik attempted to win custody over Anders but was unsuccessful, and he lost touch with his son when Anders was a teenager.

A previous book about Anders Breivik’s late mother, Wenche, portrayed Jens Breivik as a domestic tyrant.

During the murder investigation and trial, it emerged that Norwegian social services had suspected Anders Breivik was neglected at home as a child.

According to the editor of My Fault? A Father’s Story, Arve Juritzen, the book is a form of self-trial for Jens Breivik.

Jens Breivik has re-established contact his son in the last two years but has not shared the manuscript with him.