Two weeks before she died in March, Wenche Behring complained that she had been manipulated by the Marit Christensen, the veteran Norwegian journalist who had interviewed her secretly in the months after her son's attacks.
In the summer of 2012, Ms Behring terminated the agreement she had signed with Aschehoug, Christensen's publishers, and paid back the book advance of 200,000 kroner ($34,000).
But Christensen continued to work on the book, and at the end of 2012, she approached Behring, then terminally ill in hospital, with a new contract, which she signed.
Before she died Behring complained that she had not understood what she was signing with the new deal - which allowed Christensen to use all the material from their interviews, plus material from Behring's diaries, but, unlike the first agreement, offered no compensation or credit to Behring.
"According to my client, she [Christensen] acquired this material under false pretensions. Had there been money involved, you would be talking about a fraud," Hans Marius Graasvold, Behring's lawyer, told VG.
Neither Marit Christensen, her attorney Jon Wessel-Aas or publisher Aschehoug, would comment to VG about the case.
The book, titled Modern, or The Mother, is expected to be published this autumn.