DEATH COMES CALLING

By LISA BEYER/JERUSALEM

YEHIA AYYASH WAS AN EXTRAORDINARILY CAREFUL MAN. He had to be, to endure three years in the No. 1 slot on Israeli security's most wanted list. Called "the Engineer" for his bombmaking expertise, Ayyash never allowed others to fix the time or place of an appointment. Only he determined his comings and goings.

The fugitive Islamist did, however, take phone calls. And that proved his undoing. Last week Ayyash, 29, was killed in a house in Beit Lahiya, in the Gaza Strip, by an explosion from the earpiece of a telephone he was holding. His demise ended one of the most intensive manhunts ever conducted by Israeli security--a search for the alleged mastermind of the suicide bombings that have threatened the fragile peace between Israelis and Palestinians.

Officially, Israel declined to take responsibility for the killing. But a senior Israeli official confirmed to TIME that the

operation was carefully planned and was scheduled, then delayed, at least once, two days beforehand. In the West Bank and Gaza Strip, concern rose that Islamic militants would take revenge not only on Israel but also on its partner in peacemaking, the Palestinian Authority headed by Yasser Arafat. An Islamic backlash could hamper the smooth running of the first Palestinian general elections, scheduled for Jan. 20.

The break in the Ayyash case, according to the senior official, came a month ago, when Israeli agents traced the number of the mobile telephone he was using. Because such phones emit radio signals, they were able to keep tabs on Ayyash's whereabouts. "From then on, he was in the cross hairs and it was just a matter of time," said the official. Next Ayyash's hunters created problems with his phone line. Through intermediaries, he sent the phone for repair to a Gaza shopkeeper, who forwarded it to an Israeli mobile-phone company, whereupon security officials intercepted it. They sent back a "temporary" loaner, whose earpiece was packed with a tiny but potent bomb. On the morning of Ayyash's death, they phoned him, confirmed his voice on the line and set off the explosives by remote control.

In April 1992, Israeli security first began seeking Ayyash, a native of the village of Rafat in the West Bank, on suspicion of his involvement in armed attacks by the Islamic Resistance Movement, or Hamas. A year later, Palestinian guerrillas for the first time resorted to suicide attacks in the fight against Israel. An electrical-engineering graduate of the West Bank's Bir Zeit University, Ayyash allegedly built the device used in the initial blast, at a West Bank diner popular with Israeli soldiers. For the next three years, the tactic was used repeatedly, causing the deaths of 77 victims and the wounding of more than 300 others. Israeli authorities believe Ayyash personally built the bombs that killed 35 of them and trained another bombmaker whose work claimed 10 more victims. Israeli officials say the Engineer oversaw many logistics of the attacks--for example, deciding their time and location.

Ayyash was a solitary plotter and never let his lieutenants know anything about an operation except their own role in it. Over the years, Israeli authorities came close to catching him several times, but he managed to slip free, one time disguised as a woman. "Once when we arrived at his hideout, the coffee was still hot," says an officer involved in that raid. The Israelis believe that in late 1994, Ayyash fled from the West Bank to the semiautonomous zone in the Gaza Strip, which offered relative security from Israeli troops. Arafat's Palestinian Authority claimed to know nothing of his whereabouts. A senior Authority official, however, reportedly said that one of Arafat's security chiefs offered through mediators to help Ayyash escape to Sudan or Libya, a proposal he rejected.

Following his assassination, Islamists predictably accused the Authority--which is committed to peace--of colluding with Israel to murder a Palestinian hero. At the house where Ayyash died, hundreds of Hamas supporters chanted anti-Israel and anti-P.A. slogans. Arafat immediately called a meeting of his senior security personnel. Said Sufian Abu Zaydah, head of the Israeli desk of Arafat's Fatah organization: "The killing will create a tense security situation." It also casts a pall over the Palestinian election, mandated by the peace accords with Israel. Earlier Hamas, though declining to field candidates, rejected the idea of a voter boycott. Now, says Ziad Abu Amr, a political scientist at Bir Zeit, Hamas supporters may stay away from the polls, vote for anti-Arafat candidates or even mount "demonstrations or riots that may disrupt the campaign." In an effort to minimize the political fallout, Arafat visited the home of Hamas spokesman Mahmoud Zahhar to express sympathy over Ayyash's death.

One highly likely repercussion is a revenge attack. "Hamas will now try very hard to make a big operation," says an Israeli security official. Certainly there are many suicide recruits, and Ayyash left behind students capable of building more bombs. Even in ensuring a continuing legacy, the Engineer was a careful man. --With reporting by Jamil Hamad and Aharon Klein/Jerusalem

With reporting by JAMIL HAMAD AND AHARON KLEIN/JERUSALEM