Salim Jamil Ayyash, a member of the Lebanese group Hezbollah, has been convicted by the UN-backed Special Tribunal for Lebanon over the killing of the country's ex-PM Rafik al-Hariri in a 2005 bombing. Ayyash had been on trial in absentia since 2014. Three other defendants, also alleged to be Hezbollah members, have been acquitted by the tribunal.