When somebody is murdered and his killer is unknown, the detective's first step is to ask: who had a motive? In classic murder-mystery novels and films, the usual answer was: almost everybody. But in real life, the suspects are generally few, and pretty obvious. So who killed Chokri Belaid?
The Tunisian human rights lawyer and political leader was assassinated outside his home as he left for work on February 6, and the country erupted in violent anti-government demonstrations. His wife Basma said she would file murder charges against the ruling Ennahda Party and its leader, and the mobs in the street chanted the mantra of the Arab revolutions, "the people want the fall of the regime."
But the regime in question is the democratically elected government of a country that has already had its revolution. Tunisia was the birthplace of the "Arab spring". It held its first free election on October 2011, to elect an assembly to write the new constitution. The winner, as in a number of other Arab countries, was a moderate Islamic party.
The Ennahda-led transitional government has made some mistakes but it has shown no desire to subvert democracy. Indeed, the Islamic party formed a coalition with two secular centre-left parties after the election, and in the weeks before Belaid's murder it was in talks to broaden the coalition.
Those other parties have now walked out, demanding the cancellation of the results of the 2011 election. That certainly does not serve Ennahda's interests, and the violent protests in the streets are even more of a problem, since they might trigger a military intervention to "restore order". (The Tunisian army is strongly pro-secularist). In terms of motive, Ennahda has none. So who would actually benefit from killing Chokri Belaid?