The decision to pay a child-killer for collaborating on a book about her drew the anger of the British Prime Minister, Mr Tony Blair yesterday, and outraged the mothers of her two victims.
But Gitta Sereny, an investigative journalist, defended her decision to pay the double killer, Ms Mary Bell, and said the book, Cries Unheard, would help people to understand evil.
Bell was just 11 in 1968 when she was convicted of the manslaughter of four-year-old Martin Brown and three-year-old Brian Howe. Both were strangled and their bodies dumped, one on waste ground, the other in a derelict house.
Media coverage of her case at the time was discreet, in sharp contrast to the emotional outrage during the 1994 trial of two boys, aged 10 and 11, for the murder of three-year-old Jamie Bulger.
Bell was granted anonymity by the state on her release from prison in 1980, and has since had a daughter. Their whereabouts cannot be revealed.
A spokesman for Mr Blair yesterday said he had asked his Home Secretary, Mr Jack Straw, "to examine how the payment squares with the fact that Mary Bell has been able to have her privacy protected by injunctions".
Mr Straw told BBC Radio: "The population as a whole is deeply offended by the idea that she should be making this kind of money out of these terrible murders and so am I. In a situation like this, money should go to victims' charities and not to the person who committed the crime."
Ms Sereny dismissed as preposterous claims that Bell had been paid £50,000 sterling. "This figure has been plucked from the air. Yes, she did receive some money from me and I understand the feelings of the victims' families," she told The Times, which is serialising the book.
She insisted: "There is nothing sensationalist about it. It is an attempt to find out why this woman, as a child, committed two terrible acts and what her life has been like since."
But the mothers of the victims were enraged, saying the controversy had ripped open old wounds.
Ms June Richardson, Martin Brown's mother, said: "Mary Bell is a killer and she is being rewarded for killing two innocent victims. It is causing me so much distress. It's like Martin has been killed all over again."
The Times defended its decision to serialise the book, saying it was not sensationalist or prurient.
But the Daily Mail, arguing that Bell cannot remain anonymous and profit from the book, said: "Time has done little to erase the horror of this case."