The billionaire, who was locked in a bathroom with a Filipina nurse died from from smoke inhalation. But he is believed to have fallen victim - at least in part - to his paranoia.
Mr Safra refused to leave the bathroom, though it filled with smoke fumes, even after his wife told him on a mobile phone that police had arrived. Apparently, he feared the attackers had forced her to lie. And he feared revenge by the Russian mafia after exposing massive bank fraud. The inquiry by judicial officials and police in Monaco is focusing on Mr Safra's other nurse, the man who raised the alarm. The unnamed man, an American in his early thirties, had been working for Mr Safra, 67, since July.
He said he was stabbed in the leg by two hooded men on the landing of the lower floor of Mr Safra's heavily protected, split-level apartment in Monaco early on Friday. He said he staggered down four flights to give the alarm to the security guards on the ground floor. Soon after, the fire broke out.
No one else saw the intruders. They were not recorded on security cameras in the building or in the streets. The nurse, who was questioned at length by police on Saturday and again yesterday, is in hospital with leg wounds.
"The nurse is the only witness and everything turns on his testimony," said the chief prosecutor of Monaco, Daniel Serdet. He said he was surprised that no bodyguards were present at the time.