But the biggest investigative lead yet points to Teheran. NEWSWEEK has learned that U.S. intelligence officials have evidence that Iran has funneled money to Sheik Omar Abdel-Rahman, the fiery Egyptian fundamentalist cleric whose followers at the Jersey City mosque where he preaches include bombing suspect Mohammed Salameh. Intelligence sources won’t specify the amount of the subsidy or the frequency of the payments. But they have confirmed that the money traveled from Iran to Rahman through one of his wives in Cairo. And investigators say there is as yet no connection between Teheran and German wire deposits to at least three U.S. bank accounts that the government says were held by the two suspects in custody-Salameh and Nidal Ayyad. But the FBI is looking for evidence that their money also has Iranian origins.

There are compelling reasons to suspect an Iranian connection. State Department officials believe that Teheran is responsible for a string of recent terrorist episodes, including the murder of three Kurdish politicians in Germany last fall and the slaying of a Turkish journalist last January. Last week Thomas McNamara, State’s top counterterrorism official, told a congressional committee that Iran “continues to be the most serious and deadly sponsor of international terrorism.” U.S. experts say Iran has been a major underwriter of Islamic terror in Egypt, where Rahman, now living in American exile and fighting deportation, was acquitted of charges that he ordered the 1981 assassination of President Anwar Sadat. “The Iranians are behind Sheik Rahman,” says Vincent Cannistraro, a former CIA counterterrorism analyst. Barbara Nelson, Rahman’s attorney, denied the allegation. Rahman has also denied any role in the bombing.

These suspicions are leading investigators to a closer look at Hizbullah, the radical Shiite fundamentalist group sponsored by Teheran. Congressional and State Department analysts say Iran’s usual mode of operation is to designate a surrogate group to arrange an attack using local hires. Again, investigators have nothing to connect Hizbullah and the German bank deposits to Salameh and Ayyad. Factions of Germany’s large and politically active Muslim community (an estimated 2 million) have strong terrorist links. But analysts say the country may only be a transit point for the cash. “The actual bankroller for this bombing may be two or three steps away from Germany,” said one official.

The stateside investigation continued to unfold rapidly. Salameh’s March 4 arrest led authorities last week to Ayyad, 25, an engineer for Allied-Signal, the giant Morristown, N.J., chemical company. Sources say the two men opened at least three bank accounts last year (including at least one joint account), each of which received overseas wire transfers in amounts just under $10,000-the threshold that triggers federal reporting requirements. Salameh’s lawyer, Robert Precht, says the funds were loans from relatives. According to a federal complaint, Ayyad and Salameh cosigned a rental agreement for a red Oldsmobile similar to the one witnesses say Salameh drove to a Ryder truck-rental office in Jersey City on Feb. 23. It was there that Salameh acquired the van that investigators believe carried the bomb to the World Trade Center garage. Officials say records from Feb. 25-the day before the blast-indicate that Salameh called Ayyad’s work number at Allied-Signal at least four times. The calls were made from a pay phone near the Jersey City storage shed where agents seized bomb-making materials that now appear to match chemical traces found in blast debris.

The two are an unlikely pair of possible coconspirators. Both are devout Palestinian Muslims with family roots on the West Bank, but the similarities end there. Salameh, who entered the United States on a now expired tourist visa, has held a string of low-level jobs. Ayyad was a success story. A naturalized citizen, he graduated from Rutgers University in 1991 and landed a job as an engineer at Allied-Signal. He and his new Jordanian wife are expecting their first child.

His behavior in the aftermath of the blast, like that of Salameh’s, is puzzling. It’s not clear why he stayed so close after Salameh’s arrest. But federal authorities still regard both men as “foot soldiers” who did not act alone. Investigators continue to look at the possible involvement of El Sayyid Nosair, a fundamentalist Muslim with links to both Rahman and Salameh, who was tried and acquitted in the 1991 assassination of radical Zionist Meir Kahane. He is currently serving a prison term on weapons charges. Last week New York police said they would reopen the Kahane case to search for leads that might help the bombing probe. It was a sign that despite early luck and high-profile arrests, the government was still a long way from answering two central questions: who and why?