(KUNA) -- Lebanon's Chief Military Investigating Magistrate Rashid Mezher has started questioning suspects of the Fath Al-Islam network the government said was involved in blowing up two buses in northern Lebanon last month, sources told KUNA on Wednesday. They added that Magistrate Mezher would issue bills of charges for the four suspects.Meanwhile, the Director of Internal Security Ashraf Refi said that the network had been discovered five days before and that its elements were later arrested in various parts of the country. "The network was discovered when enough intelligence was gathered. We do not control the timing, but we act according to the security information we get starting with the first clue, then confessions, until evidence is verified. Then, findings are revealed to the public, substantiated by adequate documents." The Lebanese Interior Minister Hassan Sabaa said yesterday that four Syrian nationals from Fath Al-Islam network had been arrested and owned up to blasting two buses in the village of Ein Alak on February 13 which killed three people and injured 20 others.