Sabri al-Banna, better known by his nom de guerre, Abu Nidal (father of the struggle), was central to my introduction to Middle East politics. After the slaughter of six customers at a Jewish delicatessen in the summer of 1982, I helped to produce a television documentary on extremist attacks in Paris. The PLO's representative in France directed me to Dr Issam Sartawi, a heart surgeon who established secret contacts with the Israelis 11 years before the Oslo agreement.
Eight of Dr Sartawi's PLO colleagues had been assassinated by Abu Nidal's gunmen. "He will kill me too," Dr Sartawi predicted when he gave me a grainy black-and-white snapshot of Sabri al-Banna for our programme. The image of the bearded and balding middle-aged killer, sitting at a desk and wearing fatigues, was the first ever released.
Sabri al-Banna was a psychopathic killer, a gun for hire who had been recruited by the Israeli intelligence agency Mossad, Dr Sartawi said. He believed Mossad had staged Abu Nidal's attempted assassination of the Israeli ambassador in London, Mr Shlomo Argov, in June 1982, so that Israel would have a pretext to invade Lebanon.
Incredible as the story may seem, it is widely believed by Palestinians. I never saw Dr Sartawi again: Abu Nidal's men shot him dead in the lobby of a Portuguese hotel in April 1983.
The US State Department calls Abu Nidal's Fatah Revolutionary Council (FRC) "the most dangerous terrorist organisation in existence" and blames him for the death or injury of 900 people in 20 countries since 1973. Atrocities attributed to him include the 1973 bombing of a Pan Am jet that killed 32 people in Rome and the 1974 explosion of a TWA airliner in which 88 passengers perished.
In December 1985, seven of his gunmen murdered 18 bystanders at El Al counters in the Rome and Vienna Airports.
If he is alive - and his demise has been announced several times before - Abu Nidal is 61 years old. Over the past week, a spate of reports in keeping with his mysterious and evil legend have claimed that al-Banna has been arrested by the Egyptians and/or is dying of leukaemia in a Cairo hospital. Arab sources suggest he was shopped by his last mentor, Col Muammar Gadafy, in an attempt to obtain the easing of UN sanctions against Libya.
These reports were categorically denied by the Egyptian Foreign Minister, Mr Amr Musa, yesterday. But Mr al-Banna is not the sort of guest - or prisoner - that any Arab government has ever admitted to having, and Mr Musa's denial convinced no one.
In many ways, Sabri al-Banna is the negational alter ego of the man he wanted to assassinate, the Palestinian Authority President, Mr Yasser Arafat, who is eight years his senior.
The lives of both men were determined by the mass expulsion of Palestinians from the newly founded state of Israel in 1948. Sabri al-Banna's father, Khaled, had been a wealthy orange grower in the coastal city of Jaffa. But at the age of 11 he became a refugee in the West Bank town of Nablus, where he wore ragged clothes, ran errands and survived on charity.
As young men, both Arafat and al-Banna sought fortune in rich Gulf countries. The two were founding members of the main PLO group, Fatah, in 1964, but they quarrelled and in 1973 al-Banna formed the FRC.
Could Abu Nidal have worked for Mossad, as Dr Sartawi claimed, just as he worked for Syrian, Iraqi and Libyan perpetrators of dirty deeds? When he is gone, more than one Arab dictator will heave a sigh of relief. It would be the ultimate irony for a man so steeped in blood to drift off between white cotton sheets.