How did two men, armed only with knives, reach the armoured apartment of the banker Edmond Safra, one of the richest men on the planet? How did they set fire to the apartment (if they did)? How did they escape without being seen by the guards at reception or by any of the 130 security cameras that spy permanently on the streets of the principality?
Monaco is reckoned to have over a thousand billionaires and millionaires in official residence. Along with entertainers such as Ringo Starr and Shirley Bassey, supermodels such as Helena Christiansen and Claudia Schiffer plus the photographer Helmut Newton, and a plethora of top- earning sportsmen and women including Martina Navratilova, Michael Schumacher and David Coulthard, the principality is also home to obscure Russians who have come by their money rapidly and less publicly.
The attraction of "The Rock" to the rich and idle - and the rich and energetic - is partly its tax-free status, but partly its reputation as a place where violent crime is virtually unknown. The murder rate in Monaco stands at roughly one per decade. There has not been an unsolved murder since the 1960s. There is one policeman for every 60 people. Local legend states that you can stroll back from the casino in furs and jewels to your unlocked car at 2am, without fear of being attacked.
No more. The strange death of Mr Safra, a Jewish-Lebanese billionaire banker, a resident of Monaco for 20 years and a personal friend of Prince Rainier, will spread fear throughout the luxurious apartments and villas of the principality. The mystery surrounding his death and that of his family nanny continues to deepen. The authorities in Monaco are expected to launch a murder investigation tomorrow, but officials said there was no clear evidence that the fire that swept through his heavily protected apartment on Friday morning was started deliberately.
The facts of the case do not easily fit the theory circulating in the financial world of a contract killing. But the other possibility - a burglary that went badly wrong - also appears far-fetched.
Mr Safra, 67, and the nanny, Viviane Torrent, a Frenchwoman in her early thirties, were suffocated by fumes after locking themselves in a bathroom to escape two hooded men armed with knives. The intruders had stabbed Mr Safra's male nurse (earlier described as a bodyguard) as he went out of the door of the apartment in the early hours.
His Brazilian-born wife, Lily, locked herself in another room and escaped unharmed. Mr Safra and Ms Torrent were found dead in the bathroom when firefighters brought the blaze under control two hours later.
Originally, sources in the investigation said that the fire appeared to have been started deliberately, outside the apartment, spreading to the roof and interior. But Francois Serdet, the chief prosecutor of Monaco, said it was not yet clear whether the fire had been lit by the intruders or began accidentally in the confusion of the raid.
"Everything turns on the evidence of one man, the nurse," said Mr Serdet (who is, like the Prime Minister and the chief of police, a Frenchman, appointed by the state of Monaco on the recommendation of the French state). The nurse, who has not yet been named, was being interviewed by police yesterday at the Princess Grace Hospital, where he was being treated for stab wounds to the thigh and lower leg.
Mr Safra, whose family built its first fortune on camel trains in Ottoman times, had created a financial empire in New York and Luxembourg in the last 30 years. The $10.3bn (pounds 6.4bn) sale of his two banks - Republic New York Corporation and Safra Republic Holdings of Luxembourg - to the London- based banking giant HSBC, is due to be completed early in the new year.
Banking industry sources have speculated on a possible "Russian connection" to his death and said Mr Safra had told friends that he knew there was a contract on his life. It was his Republic New York bank that blew the whistle last year, in a letter to the FBI, on alleged embezzlement and money-laundering of hundreds of billions of dollars of international aid to Moscow.
But if this was a professional, contract killing, why were the intruders apparently armed only with knives? Equally, if it was a petty burglary, how did they reach the split-level apartment, guarded by armoured doors, at the top of one of the most heavily protected buildings (also containing three banks) in the heart of the wealthiest part of the principality? Why did the security guards at the entrance see them neither arrive nor leave?
The alarm was given by the male nurse, who staggered down the stairs after being stabbed, to warn the guards. When firefighters and police arrived they had enormous difficulty in reaching Mr Safra and his family, partly because the apartment was ablaze, partly because the armoured doors had been closed.
Whether Mr Safra died by accident or design, however, is irrelevant to the polyglot population of Monaco, who have nothing in common beyond their wealth. If the principality were to lose its reputation as a safe haven for the rich, many of its most famous residents would have little reason to remain.
BUSINESS, PAGE 3