Author Gitta Sereny said last night she had warned Mary Bell against going ahead with a book about her murders of two young children, telling her to talk to a psychiatrist instead.
But Sereny said she had no regrets about publishing Unheard Cries.
"I warned her against doing it, that it would be better for her to speak to a psychiatrist for her great desire to open herself, to reach inside herself, but she was determined to do this," she told Channel 4 News.
Ms Sereny said she wrote the book anyway because "I really wanted to go ahead with her knowing absolutely what she was in for.
She condemned the outrage over the book as "the most shameful manipulation of a population that I have ever seen". But she insisted she had no regrets about doing the "extremely serious" book. "It's a very painful book to read."
She and publishers Macmillan had been in frequent touch with the Official Solicitor, guardian of Bell's daughter's interests, she said.
Earlier, the British Home Secretary, Mr Jack Straw, started an inquiry into how the child killer was paid for her collaboration on the book, writes Rachel Donnelly. It has emerged that officials from the Home Office were informed two years ago that such a book was being planned.
The announcement came after Mr Straw met Mrs June Richardson, the mother of Mary Bell's first victim, who has demanded that Bell should return the money she was paid for her collaboration on the story of the murders of Martin Brown and Brian Howe. Mr Straw told Mrs Richardson (who has since remarried) that he shared her "anger and frustration" that money had been gained from the "terrible circumstances" of her son's death, but Mrs Richardson remained critical of the book deal being allowed to go ahead.
Speaking after the meeting with Mr Straw, she insisted the money should be returned and handed over to a charity and that any profits made by Sereny should also be given to charity.
Mr Straw greeted with dismay the discovery that Durham Probation Service had informed a junior official at the Home Office in early 1996 that there was a "possibility" of a book being written. The revelation came after journalists spoke to Mary Bell's former partner, who told them the Home Office knew of plans for the book. But Mr Straw insisted that the information was not passed on to ministers.
As the controversy over the book increased, the Press Complaints Commission announced it was launching an investigation into whether the London Times breached its code of conduct by paying for serial rights. The code of conduct bans payments to agents or associates of convicted criminals unless it can be proved there is an overwhelming public interest.
In the House of Commons, the Attorney General, Mr John Morris, has appealed for Mary Bell's daughter, who is currently in hiding with her mother, to be protected from "press frenzy or mob rule".