Tragic, unpredictable . . . lessons to be learnt. Whatever the outcome of the Madeleine McCann case, there will be no lack of inquest afterwards on the way the Portuguese police have handled the case. In some ways it has already begun. The British view, thinly disguised, suggests that things would have been better handled here. It is, at best, a questionable assumption. When it comes to the psychological profiling of determined predators, we too have a long way to go.

Tomorrow three women who have lost daughters to violent attackers are taking the courageous step of holding a press conference in London to highlight the failure of our criminal justice system to understand and to pre-empt the actions of men whose obsessions drive them to stalk, control and sometimes to kill their victims. Stella Moore, Tricia Bernal and Carol Faruqui have all experienced the agony – shared by Kate and Gerry McCann – of finding themselves daily in the headlines as police pieced together the steps that led to a family tragedy. In their case, it was the loss of their grown-up daughters, killed by estranged and vengeful partners, which turned their lives upside down.

Stella Moore’s daughter, Tania, was shot in her car near her home in Derbyshire. Tricia Bernal’s daughter, Clare, was shot dead in Harvey Nichols by a former boyfriend. Carol Faruqui’s daughter, Rana, was stabbed to death in a field while tending her horse. What all three mothers now know is that, in each case, there were unmistakable clues that pointed to the violent outcome – the assailants were known to the victims, police had been informed about the threat as it built up and a steadily growing series of events pointed forwards to the almost inevitable final confrontation. Yet on each occasion the clues were misread, downplayed, dismissed or ignored.

The case that the three women will be making is a dramatic one. They believe that, if police and social services studied techniques now routinely used in countries such as America, Canada and Finland, but which are radically different from those deployed in Britain, 80 per cent of the deaths that are likely to happen over the next three years could be prevented. And since, on average, two women die each week in this country at the hands of a current or former partner, that is a substantial claim.

Domestic violence killings, as they are known, have a pattern that has been studied in great detail in the United States, leading to a dramatic reduction in the number of cases. Some years ago, two men, Bob Martin, of the Los Angeles Police Department, and Gavin de Becker, who specialised in protecting film stars and other public figures from the attention of stalkers, began to compile a system of assessing the risk of assault from rejected partners or psychopathic stalkers. By studying hundreds of cases, and working backwards from the actual assault to the first signs of a possible threat, they realised that there was a method by which the risk could be accurately quantified.

They developed Mosaic20, a computerised model that assessed the likelihood of an attack, placed it on a scale of one to ten and measured it against nationally compiled statistics. So accurate did their predictions become that San Diego, where such attacks were common, was persuaded to set up a family justice centre, where anyone believing that they may be at risk can go for expert assessment and, if necessary, protection. The centre has been instrumental in reducing the domestic murder rate from 12 a year to just one. It has now been copied in 26 other parts of America.

In Britain, there is only one such system in use. The family justice centre in Croydon, introduced a year ago, is a model of its kind, as good as anything elsewhere in the world. In an area where there were up to five adult murders a year, the number has dropped to zero. It has yet, however, to be copied anywhere else, and it has minimal funding compared with the US model. Baroness Scotland of Asthal, the Home Office Minister, has been pressed to introduce it in Britain but has not yet been persuaded. Tomorrow she will be lobbied by Stella Moore, Tricia Bernal and Carol Faruqui to support the Croydon centre and to apply its principles more widely across the country.

There is, of course, no evidence that the person or persons who abducted Maddy McCann would have shown up on an equivalent computer model for child-obsessed adults. But there are strong parallels when it comes to the use of psychological evidence.

Determined stalkers, fixated on their likely victims, whether children or adults, leave trails of evidence – strange patterns of behaviour, psychological flaws, bizarre and sometimes violent episodes – that can be followed as scientifically as fingerprints or DNA evidence, which are the standard raw material of police investigators everywhere. The difference here is that the violent act, whether murder or abduction, has to be predicted before the event, rather than unravelled afterwards, and detectives seem less enthusiastic about preventing crime than they are about solving it.

When it comes to the kind of psychological profiling that might have prevented the Soham killings, for instance, where all the clues were available in advance, our systems are ill-equipped to take preventive action. We must all hope that there is a happy ending to the Maddy McCann case. But, if the worst transpires, one thing is certain. When all the facts are known, and the abductor identified, the clues that might have identified him in advance will be staring us in the face.

Times Recommends

• The ghost of Robin Cook haunts Chilcot’s feast
• The truth shouldn’t need oaths
• Violence: let’s separate the men from the boys