In the Syrian capital Damascus, the official version is that Kanaan commited suicide by shooting himself in the mouth. The government issued a statement mourning his death but gave no details.
But few in the region appear to believe the official version of events. Professor Hilal Khashan is a professor of political science at the American University of Beirut.
"People usually don’t commit suicide at the age of 63, especially if they had a successful career," Kanaan said. "And the reports about his behaviour and his composure at the latest cabinet meeting in Damascus pointed out that he was calm and that he looked upbeat. So, the news about his suicide sounded most unusual. You know, intelligence men tend to be tough people."
Like thousands of others, Khashan listened to Kanaan speaking on Lebanese radio shortly before the announcement of his death was made. At the time, Kanaan suggested this might be his last statement. He sounded like a man who knew his days -- hours as it turned out -- were numbered.
But if it was not suicide, what was the Syrian government's motive for disposing of one of its most loyal servants?
A hint can be found in an interview given this week by President Bashar al-Assad to CNN. If the UN investigation into the death of former Prime Minister Hariri concluded that Syrians were involved, he said, they would be charged with treason.
The UN investigation into Hariri's assassination in February is due out next week and is expected to point an accusing finger at Damascus. Ghazi Kanaan was questioned by the UN investigators just three weeks ago in Syria. Professor Khashan said he has no doubt that the Syrian authorities wanted to get him out of the way quickly.
"This man was critical in Lebanon and he was in control of the Lebanese file for Syria, so when you assassinate him you create a gap in investigation," Khashan said. "This man was a security official. Security officials don’t act on their own, they implement directives by their superiors.”
The massive car bomb that killed Hariri and nine others and blew a hole 10 meters deep in a Beirut street has had catastrophic consequences for Syria. It led to massive political protests in Lebanon, international opprobrium, and, in May, withdrawal of all Syrian forces from the country.
If the UN report were to confirm suspicions that Syria was behind the killing, the international pressure on President al-Assad would become even more intense.
The United States' patience with Syria is already running out over its alleged failure to prevent the infiltration of arms and insurgents across its border into Iraq. U.S. President George W. Bush said yesterday that he did not want to prejudge the UN report into the Hariri assassination but warned that he expected more of Damascus.
"I think it's important for Syria to understand that the free world respects Lebanese democracy and expects Syria to understand that the free world respects Lebanese democracy and expects Syria to honor that democracy," Bush said. "You know, it's one thing to have been asked to remove the troops and all intelligence services. Now the world expects Syria to honor democracy in the country of Lebanon."
Against this background, so the argument runs, Ghazi Kanaan had become too dangerous to be left alive; he knew too much and showed no sign of being willing to play the role of scapegoat for decades of Syrian policy. His death, on the other hand, removes a potentially fruitful line of investigation and allows the Syrian authorities to blame a man who can no longer answer for himself.