Agnès Poirier: To see ourselves as others see us

The parents of two French students murdered by men who should have been in custody are outraged. So should we be

It often takes a foreigner to see things not only more clearly but differently; for us to understand who we are; to recognise our strengths as well as our weaknesses. And it often takes a foreigner to make us feel ashamed of things we have learnt to endure passively. Reflected in their eyes, suddenly things we have simply put up with fill us with horror.

Last week, the British only had to see the faces of Guy Bonomo and Françoise Villemont, the parents of the French students savagely murdered in London last year, and to read their dignified and moving statements, to feel disgust at the shortcomings of the British justice system. As Jack Straw admitted, the two murderers "could and should have been in prison at the time of the killing". A series of unimaginable and appalling blunders at every level of the justice system – the police, the courts, the prison and the probation services – allowed the murderers to torture and kill two research scientists with brilliant futures.

Didn't we say at the time that the murder of John Monckton in 2004, committed by another convict who should have been in prison at the time, and was considered as the unfortunate result of a "collective failure" by probation and prison staff, would surely put an end to such possibilities.

But the murders of Laurent Bonomo and Gabriel Ferez might just mark a new beginning for Britain's probation system. Why this case and not another? Not only for the particularly atrocious ways the two students died, the details of which stunned the whole nation, but because they are foreigners: Laurent and Gabriel were guests to this country.

There is nothing more shameful than to fail those who come to you with an open mind and healthy curiosity, a generous predisposition towards your culture and way of thinking. Laurent and Gabriel were indeed overjoyed to be accepted for a three-month placement at London's Imperial College. For biochemistry students from Clermont-Ferrand in central France, Imperial College, in particular, and Britain in general, represent one of the most prestigious goals in the world of science.

Britain's universities are full of enthusiastic students from all over the world who spend the best years of their lives in Britain and go back home with memories they will always cherish. They love the vibrancy of their city and embrace British culture – complete with its little prejudices – lending the country, in return, a part of their youth, optimism and dynamism. But when their lives are taken away in such tragic circumstances, the failure of the system becomes the very hosts' failure. When did we go blind? Why didn't we react before, hosts start wondering.

I felt the same embarrassment when the young Caroline Dickinson was murdered in 1996, at Pleine-Fougères, a little Breton village I know well. A lovely 13-year-old had pleaded with her parents to let her go on a trip to discover France and learn French. Her interest for France lead to her brutal death at the hands of a ruthless predator, one that might never have been caught had it not been for the persistence of her father.

Caroline's was a shockingly botched case. There had been many flaws in the French investigation. A wrong suspect was arrested, leaving time for the murderer to flee to the United States. It took eight long years, during which John Dickinson campaigned and set about exposing the police investigation, for the French Justice to finally find and bring to court the murderer, a Spaniard.

Caroline's killer may not have been French and the French justice system may not have failed the Dickinson family the way the British one has the Bonomos and Ferezs, but the feeling of infamy remains, only perhaps because the victim was a guest, more vulnerable to an environment she didn't know; her family having to battle against a system they did not understand.

Many Portuguese people must have felt the same way when Madeleine McCann disappeared from their idyllic seaside resort and their police were seemingly losing time in the crucial first days of the investigation. I have many Italian friends embarrassed both by the murder of British student Meredith Kercher in Perugia and much of what transpired since.

Of course, misunderstandings can take a grip and be exacerbated by cultural differences. Remember how, in the case of Madeleine McCann's disappearance, the British press viciously attacked the Portuguese judiciary system and its representatives, often only out of sheer ignorance. The Portuguese police reacted by making the parents "official suspects".

Great expectations can lead to great disappointments. British institutions are generally held in high regard throughout the world. The shock of Laurent Bonomo and Gabriel Ferez's parents on learning of this breakdown of the judicial system in protecting their sons is all the greater given the high hopes they originally had in such an admired system. Imagine their horror, their sense of betrayal, when they realised that this very system was indirectly responsible for their children's killing. Last week they announced that they would sue Britain for failing its duties, and who can wonder?

It can take a foreigner to see the failures in our midst and to address them in a way we would perhaps never have dared ourselves.

Would the parents of Jean Charles de Menezes, the innocent Brazilian man shot by the police at Stockwell tube station, have pursued their case so far had they been British? The relentless campaigning of Caroline Dickinson's father, John, allowed for instance the first DNA testing of a whole village, a procedure which had never been done before in France. He was also key in the appointment of a new investigative magistrate in charge of his daughter's case, a very rare action in France.

Guests should not need to contribute to putting their host's house in order. But sometimes it takes a foreigner....