Sicilian magistrate Dolcino Favi said today that a team of four Italians investigating the Achille Lauro hijack had "reconstructed the killing of the American in all its details."

Speaking at a ship-board news conference after the cruise ship returned to its home port here today, Favi said that because pretrial investigations are secret in Italy he could not reveal those details. But he said it was now clear why, how, where, when and by whom the disabled American, Leon Klinghoffer, was murdered and the body thrown overboard.

Implying that the magistrates now know who did the killing, he said only that the four Palestinians now in jail in Spoleto, in central Italy, would all be tried on charges of "involvement in premeditated murder."

Favi and the other three magistrates boarded the ship yesterday as it passed through the Straits of Messina and completed their probe of the slaying en route.

The judge also cast doubt on an earlier version of how the hijacking had been set off by appearing to deny that the hijackers had been discovered by a waiter while they were in their cabin cleaning their weapons.

Asked if that version was correct, he smiled disparagingly and shook his head. But he did not say whether this reaction implied a judgment on reports that the Palestinians were on their way to Ashdod, Israel, and took over the ship only when they were discovered.

Favi said there were "perhaps six or seven, maybe ten" witnesses aboard the ship. News reports had named five key witnesses.

As the 23,629-ton liner sailed into Genoa port, pulled by a large orange tugboat and escorted by several police launches, its brightly lit decks were crowded with what appeared to be most of its 313 returning crew members who smiled, waved flags and made the V sign for victory. Nineteen passengers also remained aboard, together with the four magistrates and 20 police officials.

As the ship's foghorn sounded several short blasts and loudspeakers blared the ship's Neapolitan theme song, "La Nave Blu," hundreds of rejoicing family members waved to the sailors. Later, all the family members were allowed aboard for joyous and tearful reunions. "It was terrible, horrible," wept a gray-haired man supported by a younger man and a woman.

The captain, Gerardo de Rosa, said that when the hijackers disembarked from the ship in Port Said, Egypt, he had "not been sure" that a missing American had been killed.

Besieged by journalists and cameramen in a lounge of the ship, de Rosa said that although the Palestinians had told him that they had killed a passenger and given him the passenger's passport, "it was not certain; I was not sure about it" at the time the terrorists left the ship.

Clearly aware that he has been accused of concealing Klinghoffer's murder until after the four hijackers had gone free, the officer said he now had no doubts that the hijackers were guilty. But he had not reported the crime before they left the ship "because I did not see it, nor did I hear any shots. I hadn't actually seen anything."

He added that although other people on the ship did see the killing, they had not immediately reported it to him because "they weren't able to talk to me." He said that he was guarded by the Palestinians "every second" after they took over the ship Oct. 7.

De Rosa said it would be difficult to tell the entire story in a short time because "they were long days for me. It was as if years passed on my shoulders." But he said he was in his cabin when the second officer burst in to tell him there were terrorists on the ship.

"I rushed out, heard the sound of machine-gun fire, took the service stairs to the navigation room and found two of them there. Then we went to the bridge where the officers had been forced to lie down and they told me they had taken control of the ship." He said the terrorists, who said they were fighting for the liberation of Palestine, said they had 20 men. "And I felt that it was opportune for me to believe them."