The day after the accident the Lebanese DGCA included the following in a statement to the press. The aircraft was cleared to descend to 11,000ft at 0032Z and at 0037Z further cleared down to 6,000ft. At 0044Z pilot reported 90 miles northeast (?) of the airport and reported again when 40 miles from the airport, estimating overhead at 0052Z. There was then apparently no further contact with the flight. The aircraft crashed into the sea 6 miles off shore.
A brief summary of the accident in the ICAO Adrep system based on 'Lebanese State File' AC0175 adds that the ILS was unserviceable and the the aircraft would have been visual below cloud with 20km visibility. The report goes on to say that eye witness reports of 'fire or explosion' could not be substantiated and that there was no evidence of an explosion or fire on any of the bodies autopsied, although 'one nylon jacket showed evidence of heat.'
This accident used to be included on the US governments list of 'criminal acts against aircraft', apparently based on the early reports of an 'explosion' and that 'the noise of the crash had sounded more like an explosion than impact with water'(!) but was removed in about 1981 after a review of available information did not substantiate these reports.
It could have been a bomb or it could have been that the pilot just flew into the sea (visual approach on a dark night over a dark sea with the only visual reference being the distant lights of Beirut - it's happened before).
All the rest about the PLO office and who or what might or might not have been onboard is interesting but, by itself, is evidence of nothing.