Roula Khalaf sums up the crisis and explains why Hezbollah’s potential indictment could make Lebanon unstable:

The alleged involvement of Hizbollah is a perilous outcome for the country: the movement is now part of the coalition government led by Saad Hariri, the prime minister and son of the dead leader. [..] Hizbollah, whose military organisation is more powerful than the Lebanese army, will not hand over any suspects. Nor will the government be in a position to arrest anyone.

The question nobody seems to know the answer to is: What if Hezbollah was indicted? What can be done about it?