Rome trial opens for eight men accused of plot against the Pope. Prosecution hopes to prove Agca was part of international conspiracy

The trial of three Bulgarians and five Turks charged with conspiring to murder Pope John Paul II opened in Rome Monday. The case against the men is being heard in the same converted gymnasium where the terrorist murderers of former Italian Prime Minister Aldo Moro and the kidnappers of United States Brig. Gen. James L. Dozier were convicted.

Judge Severino Santiapichi is presiding, the same man who was in charge of the brief trial of Mehmet Ali Agca in July 1981. The judge sentenced Mr. Agca to life in prison for shooting the Pope in St. Peter's Square in Rome on May 13, 1981. During those proceedings, Agca confessed to trying to kill the Pope but insisted he had acted alone.

In their first interrogations of Agca in May 1981, however, Italian authorities gathered evidence of an elaborate support apparatus behind him, including a Bulgarian connection.

Judge Santiapichi did not pursue this in the trial. But in his formal verdict, issued on Sept. 25, 1981, the judge declared Agca had been part of a conspiracy ``aimed at promoting . . . terrorism and creating the conditions for the destruction of established social order.'' He recommended the case be kept open.

In October 1981 another respected Italian magistrate, Judge Ilario Martella, was charged with investigating whether there was sufficient evidence to support charges that Agca was part of a conspiracy to kill the Pope.

Judge Martella took three years. In October 1984 he delivered to his superiors a 1,243-page summary of more than 25,000 pages of testimony. On the basis of his report, an indictment was issued against the eight defendants.

In the trial, the prosecution will use almost all the information he collected to try to prove that Agca and his close friend, Oral Celik, were the instruments of a conspiracy by the Bulgarian secret service to assassinate the Polish Pontiff.

Two Bulgarian Embassy officers under indictment, Todar Aivazov and Zhelyo Vasilev, returned to Sofia in the summer of 1982 and are being tried in absentia.

The third, Sergei Ivanov Antonov, a Bulgarian airlines representative who had no diplomatic immunity, remained in Rome and was arrested on Nov. 25, 1982. (The four Turkish defendants are Agca, Musa Serdar Celebi, Bekir Celenk, and Mr. Celik.)

Why Mr. Antonov did not leave Rome as well is only one of many questions that may be answered in the course of the current trial. Bulgaria says Antonov remained in Rome because he had no connection with the attempt on the Pope. Agca's allegations to the contrary are slander, the Bulgarians say.

And, indeed, Antonov emerges from Judge Martella's investigation as a secondary figure in the alleged plot. But it has been confirmed to Martella's satisfaction, by meticulous investigation of meeting places and cross examination of witnesses, that Antonov did have direct contacts with Agca during the final weeks before the shooting. It will be interesting to see whether Antonov confirms any of this in the course of the trial.

As a result of investigations in connection with still-continuing trials in Turkey, a great deal of information has emerged that links Agca to Turkish arms- and drug-smuggling figures.

In the days after the Pope was shot, various individuals in the West saw Agca as a demented loner, a rightist, or a religious fanatic. But the investigations by the Turks and Italians do not support such explanations for Agca's violent act in St. Peter's Square.

In fact, he is known to have had links with the Bulgarians three years before he shot the Pope.

In 1983, Turkish prosecutors reopened investigations into the 1979 murder of Abdi Ipekci, a liberal Istanbul newspaper editor and one of Turkey's most respected figures. Agca had confessed to that murder but escaped from prison in November 1979 while his trial was under way.

The Turks, during their new inquiries, obtained Agca's admission that he and Celik were working with the Bulgarians, in association with a well-known Turkish communist, Teslin Tore, in the summer of 1978. Agca identified Abuzer Ugurlu, a reputed Turkish-mafia godfather, as his sponsor in planning Mr. Ipekci's murder.

Later, one of Mr. Ugurlu's partners, Mr. Celenk, supported Agca in the Bulgarian capital of Sofia, on route to Rome, provided him with contacts in Europe, and channeled money to him.

Celenk, who is married to a Turkish actress and who cultivated an international playboy image while operating a network of European and Middle Eastern corporations out of Sofia, was in London when Antonov was arrested. Celenk flew quickly to Sofia and has not set foot outside Bulgaria since. The Bulgarian government has refused repeated Turkish and Italian requests for his extradition.

One of Agca's main contacts in Europe as he prepared for the shooting in St. Peter's Square, Musa Serdar Celebi, lived in Frankfurt.

Although he was known as a prominent Turkish rightist, Mr. Celibi had ties to Celenk, and he appears to have played an important role in supporting Agca in his attempt on the Pope's life. Celebi was extradited to Italy from West Germany in January 1983.

Another Turk on trial in Rome is Omer Bagci, who was extradited from Switzerland. He provided Agca with the gun he used to shoot the Pope, but little else is known about his connections with Agca.

Of the absent defendants in the Rome trial, Oral Celik remains the most mysterious. Martella's investigation concluded that Celik had been present in St. Peter's Square and had allegedly shot at the Pope, grazing him. Celik then disappeared completely. The Italians speculate that he may have been spirited to Bulgaria in an international transport truck for which the Bulgarian Embassy in Rome had obtained special clearance on the very day of the shooting.

Paul Henze served on the National Security Council during the Carter administration. He is now a consultant for the Rand Corporation in Washington, D.C. KEY FIGURES IN THE TRIAL IN ROME

Mehmet Ali Agca: Shot Pope John Paul II in St. Peter's Square in Rome on May 13, 1981. Has since confessed to relationship with Bulgarians since 1978 when he says he was trained by them in Syria. First major crime was assassination of Istanbul newspaper editor Abdi Ipekci in Feb. 1, 1979.

Sergei Ivanov Antonov: Bulgarian airlines office chief in Rome. Identified by Agca as one of four Bulgarian contacts during his preparations to assassinate the Pope. Others left Rome before Antonov's November 1982 arrest.

Bekir Celenk: Alleged to be a leading Turkish mafia figure who operated from Sofia for many years. Linked to widespread drug and arms smuggling throughout Western Europe. On arrest of Antonov in Rome, fled to Sofia. Repeated Turkish requests for extradition have failed.

Musar Serdar Celibi: Ostensibly a representative of rightist-Turkish organizations in West Germany, Celibi appears to have played a key role in passing money and possibly guidance to Agca during final months before shooting of the Pope.

Oral Celik: Hometown friend of Agca. Appears to have been a partner in most of Agca's activity. Disappeared after shooting of Pope. Believed transported to Bulgaria in sealed international transport truck.

Abuzer Ugurlu: (no photo available) Defendant in three trials in Turkey charged with masterminding Turkish mafia operations. Testimony has identified him as a protector and supporter of Agca since 1978.