Who can claim that Damascus wanted to kill one of its own protégés?
The car bomb was massive and an armoured limousine was heat-washed by the explosives. A professional's work. But who? And why?
Mr Murr was wounded but not killed by the bomb which exploded as his convoy - smaller than the convoy in which the former prime minister Rafiq Hariri was murdered along with 20 others on 16 February - was travelling on a narrow lane in the eastern suburb of Rabieh close to his home.
How Mr Murr could survive - he was driving his own Porsche Cayenne which was almost pulverised by the explosives - remains a mystery. Two civilians, including an elderly man, were torn to pieces in the street, another 12 wounded.
The wreckage and blood were covered by pink and crimson petals, a shower of bougainvillea blasted from trees and bushes in the lane, blessing the devastation with a strange beauty.
It is a quiet neighbourhood of embassy residences - the Mexican ambassador's wife was among the wounded. Mr Murr, a Christian, regularly drove through here, often at the same time each day: assassins like people who are regular in their routes home. And of course, within the hour, the speculation started.
Mr Murr and his father had put themselves on the polling list of former rebel (and anti-Syrian) General Michel Aoun in last month's elections. Had this offended the Syrians? Enough to try and kill the president's son-in-law? Unlikely.
Then there was the al-Qa'ida theory. In September, Mr Murr said he found a plot to blow up the Italian and Ukrainian embassies in Beirut - this was news to the embassies - and he arrested 10 Islamists allegedly close to Osama bin Laden.
One of them, Ismail Mohamed al-Khatib, whom the authorities claimed led an al-Qa'ida network, died in custody. A heart attack, it was claimed. The Interior Minister was criticised. People don't just die of "heart attacks" in Lebanese police stations; not unless someone does something dreadful to them. So was this al-Qa'ida's revenge? Then there was the less sinister explanation. Lebanese politicians are often businessmen. There may have been feuds, scores to settle.
Syria denounced the attempted assassination. Saad Hariri, son of the murdered ex-prime minister, talked of "a secret hand that wants to undermine stability ... to wreak havoc in [Lebanon]." From his hospital bed, Mr Murr, wounded in the face and legs, said "the country is going through a difficult period and we all have to face that".Reuse content