By Lin Noueihed BEIRUT (Reuters) – Lebanon’s most powerful pro-Syrian security chief resigned on Monday, hours before the last Syrian forces were due to leave their tiny neighbor and end Damascus’ 29-year domination. The resignation of Jamil al-Sayyed, head of the General Security, signaled the collapse of the Syrian-installed security apparatus that had effectively run Lebanon for years. “Security chiefs are usually appointed with politics and change when it changes,” Sayyed said in his resignation letter. Sayyed said last week he was ready to step aside during a U.N.-ordered international investigation into the Feb. 14 killing of former Prime Minister Rafik al-Hariri, which sparked angry protests against the Syrians many blamed.