Secrecy rules around Alps murders echoes death of Diana

Seven weeks after the murders of four people in the French Alps, the dark mystery of Annecy remains intact. But media speculation thrives. Theory one: the "real" target was French cyclist, Sylvain Mollier, not the three members of the British-Iraqi family, the al-Hillis, who were also killed. The "proof" is that, of the four, Mr Mollier was "shot first". Inconvenient fact: it is scientifically impossible to determine who was shot first.

Theory two: a large amount of money found in an al-Hilli family bank account in Geneva (only 50 minutes drive from the murder scene) holds the key to the killings. Inconvenient fact: the Geneva account being investigated contains much less than the €1m or so reported.

Theory three: the Israeli secret service, Mossad, may have commissioned the murders. The cyclist, Mr Mollier, was a "nuclear scientist", something far too sinister to be a coincidence. Was he engaged in furtive, pro-Iranian dealings with Saad al-Hilli, an Iraqi-born engineer? Inconvenient fact: Mr Mollier was not a scientist but a middle-ranking employee at a factory supplying specialist metals to the nuclear industry. If Mr al-Hilli was engaged in some kind of nuclear-smuggling tryst in the mountains, why did he bring along his wife, mother-in-law and his two young daughters? Public understanding, in both the UK and France, has been muddled by far-fetched theories and incorrect reporting. The explanation is partly to be found in the secrecy rules of the French criminal justice system. We have been this way before. In 1997-9, following the death of the Princess of Wales, British and French media printed dozens of conspiracy theories about her fatal accident in Paris. In the total absence of information from the judge leading the French investigation, speculation, and invention, thrived. Even 15 years later, many people remember the Diana conspiracy stories better than they remember the outline of what really happened.

In France, once an investigation is handed to an examining magistrate, it is covered by le secret d'instruction. Even basic facts are not supposed to be divulged to the public. Since the media, understandably, detests a news vacuum, there are inevitably leaks. Some are genuine; others less so. Some of the leaks to the French media are reported responsibly in the British press. Some are "spun" out of recognition. Result: confusion in both countries and criticism in Britain of the "incompetence" of the French investigation.

It is more than a month since Mr Maillaud, the investigation's official spokesman, gave a press conference. Would it not be a good idea if he was to give an official update to clear away the myths? "I will consider it," he said. "But at present I have nothing very new to tell you. If we do have another press conference, it will be jointly with the British investigators."

Meanwhile, the "known knowns" of the Annecy mystery – those things which have been officially confirmed and those things which have been reliably reported and not officially denied – offer some insight into the last hours of the four victims.

Soon after 4pm on Wednesday 5 September, a British cyclist found a scene of unbelievable butchery in a lay-by on a remote forest road above the village of Chevaline, in the Haute-Savoie region of south-east France.

Saad al-Hilli, 50, an Iraqi-born engineer, his 47-year-old wife, Iqbal, and her mother Suhaila al-Allaf, 74, who had been caravanning nearby, were found dead in their BMW estate car. They had been shot repeatedly.

Sylvain Mollier, a 45-year-old local man, lay dead beside the vehicle. His body had been dragged from where he was originally attacked and his arms arranged by his sides, presumably by the murderer.

The al-Hillis' seven-year-old daughter, Zainab, was found alive outside the car. She had been savagely beaten about the head and face, and wounded by a gunshot to her shoulder. Her sister, Zeena, four, was found eight hours later, unharmed but terrified, hiding beneath her dead mother's legs.

The British cyclist, Brett Martin, a retired RAF pilot, had been overtaken by Mr Mollier on a steep, winding climb to the lay-by minutes earlier. When Mr Martin arrived, the BMW's engine was still running and the car was spinning its wheels and reversing against a steep wooded embankment. A preliminary ballistics and forensic report, leaked last week, found that only one gun was used, a 7.65 mm automatic.

French media say this was a Luger P08 – an old-fashioned weapon not commonly used by professional killers – but this has not been officially confirmed.

Contrary to an initial leak from the ballistics report, Mr Maillaud says there is no scientific way of knowing whether Mr Mollier was the first to die. The prosecutor has, however, not denied the rest of the report.

Much of the Franco-British investigation has focused on the possibility that Mr al-Hilli was targeted because of a family quarrel over money, or because of his work in the aerial surveillance industry, or for some reason connected with his Iraqi past. Investigations in France, Britain, Iraq and Switzerland appear to have yielded nothing concrete. The possibility of a planned attack on the cyclist has also been studied but seems not to be taken seriously by investigators.

Although all possible explanations remain open, there have been hints in the French media, not confirmed by Mr Maillaud, that the investigation is shifting towards the possibility that the murderer was a "lone wolf" or psychopath. But why there? Why them? Why with such an old-fashioned gun? And why was little Zainab left alive?