The case of Mr X, the Sheffield tyrant who repeatedly raped his own daughters and fathered nine children with them, is a stark reminder that pure evil of this kind is not confined to Austria. The question for Britain must now be what public agencies were doing for the 25 years in which these girls were suffering appalling abuse.

Mr X was clearly skilled at escaping detection by moving around. Should that excuse society's failure to prevent the brutality? At least one teacher seems to have expressed concern. Doctors also appear to have worried about the very high infant mortality rate of these young girls' offspring - data that must have shown up on their medical records.

It is too early to judge how effective hospitals, schools, police and social workers were in any contact they had with this family. What is clear is that the recommendations made after a horribly similar case in Swindon four years ago were not implemented in Sheffield. Swindon's serious case review advocated DNA testing in such circumstances, and the creation of a family tree. It was a simple DNA test that made Mr X plead guilty in the end. But it could have happened years earlier.

Yesterday's remarks by Lincolnshire County Council's director of children's services look pre-emptively complacent. He said that child protection systems have improved “a great deal” since these dreadful events took place. But Mr X only came to the attention of the authorities in June. The serious case review is being carried out by an independent academic for the Sheffield safeguarding children board, but it must be genuinely independent of the council.

It is essential that there is a forensic, independent review of this case. There must be no repeat of what happened in the tragic case of Baby P, where Haringey council investigated and exonerated itself. Then, it was left to the media to force greater disclosure, and to demand proper accountability.

If the system cannot be trusted to investigate its own properly, the media must expose it. Yet the media have less information about the Sheffield case than they did about Baby P. This is partly because Tuesday's court hearing was short, and partly because of reporting restrictions. The lifelong anonymity rightly given to all rape victims means that it is not possible for the media to name the defendant, because to do so might lead to the identification of his daughters. In addition, the media are unable to publish a number of other pieces of information about the family, because of the fear that disclosure of such information might jeopardise the privacy of the daughters and their surviving children.

The daughters and their children have suffered enough. Their privacy must be respected. But it is also vital that a proper assessment is made of whether public agencies did their job properly. It is not a foregone conclusion that the State failed. But it is important to understand, for example, if the daughters tried to make their plight known. One of the most unbearable aspects of this case is that they seem to have kept silent out of fear that their children would be taken into care. One called the children's charity ChildLine, but hung up because it could not guarantee that she would keep her children. It is important to know whether they have now lost their children, as they feared they would.

The media should not act as judge and jury in these cases. But if the system will not properly investigate its own, it is hard to justify the withholding of information. These poor women and their children deserve their privacy. But they also deserve openness from the authorities about what went wrong.