Similarities in the string of anti-Semitic attacks in several European capitals over the past three years have drawn investigators to the shadowy trail of the Palestinian renegade Abu Nidal.
The ''style'' of the attack against a Jewish synagogue in Rome last week was similar to previous attacks on synagogues. A team of terrorists lobbed grenades at a crowd of worshipers and sprayed them with machine-gun fire, killing one and wounding 37.
The Polish WZ-63 submachine gun they used was the same kind of weapon used in attacks against synagogues in Vienna and Brussels; in an attack on a Jewish restaurant in Paris in August that left six dead and 22 wounded; and in London, in the attempted assassination of Shlomo Argov, the Israeli ambassador. In Rome, as in the earlier attacks, no group credibly claimed responsibility.
Two French antiterrorist police have gone to Rome to explore possible links between the synagogue attack there and other anti-Semitic attacks in France.
Evidence suggests that the author of all these attacks could be one and the same - Abu Nidal.
Hassan Sabri al-Bana, better known by his code name Abu Nidal, was formerly the Palestine Liberation Organization's representative to Baghdad.
In 1974 he was condemned to death by Yasser Arafat's al-Fatah guerrilla organization on charges of embezzlement, armed sedition, and murder.
Abu Nidal subsequently denounced the ''political capitulation'' and ''treason'' of the PLO, which was in the process of modifying its strategy, and became the head of a dissident Palestinian faction.
Since his expulsion from the PLO, he has come under the protection alternately of Syria and Iraq.
He has reportedly carried out terrorist acts for both. In times of strain between the PLO and these governments, it is said that Abu Nidal carried out acts aimed at intimidating the PLO.
Abu Nidal is a mysterious figure who has seldom been photographed and never gives interviews or makes statements. The scanty information collected about his group suggests that he specializes in two kinds of attacks: against Jewish and PLO targets.
He is a prime suspect in the assassination of PLO representatives in London, Paris, Rome, and Brussels. On at least two occasions, he is known to have tried to assassinate Yasser Arafat, and Austria's pro-PLO chancellor, Bruno Kreisky.
The gunman arrested in connection with the attempted assassination of Shlomo Argov in London lastel2UFquoteHe specializes in two kinds of attacks: against Jewish and PLO targets.
el2June 3, was linked to the Abu Nidal group. That attack triggered two days later the Israeli invasion of Lebanon and the destruction of the PLO power base there.
The PLO representative in Paris has accused the Abu Nidal group of being Israeli agents. Israeli diplomats in Paris, in turn, accuse the Abu Nidal terrorist group of being no different than the PLO.
Abu Nidal has never published any manifesto explaining the aims and ideology of his group. According to French press reports, the rare Arab visitor who has met him says his only ideology is to kill.
Abu Nidal is believed to have left Syria last March at the request of Syrian President Hafez Assad. His current whereabouts are unknown.