A witness testified Friday that Mohammed Ali Hamadi calmly said "this is the man we killed" after he read an article about an American slain aboard a hijacked TWA jetliner.

Ralf Traugott, who was aboard the plane, also told the court that Hamadi, a Lebanese Shiite Moslem, threatened him by holding a gun and a grenade against his head, and told him he was a member of the Party of God and trained in Iran.Hamadi, on trial for murder and air piracy, has denied being a member of Party of God, or Hezbollah, a radical Lebanese Shiite Moslem group backed by Iran. He admitted taking part in the 1985 hijacking but denied killing U.S. Navy diver Robert Stethem.

Thirty-nine Americans were held hostage on the plane for 17 days. Stethem, 23, from Waldorf, Md., was shot and thrown onto the tarmac at Beirut's airport.

Traugott, a German-born American citizen, showed the court a Lebanese newspaper, An-Nahar, dated June 16, 1985, two days after TWA Flight 847 was seized on a flight from Athens to Rome.

The newspaper included photographs of the hijacked plane and of Stethem's body on the tarmac. Traugott said Hamadi had been reading the newspaper aboard the plane.

"I asked him what was in it," Traugott said. "He said, `This is the man we killed.' I asked him, `Did you shoot him?"'

"He said, `No, my friend shot him,"' Traugott testified. "He said it very nonchalantly, like it was no big deal."

Court document have identified Hamadi's accomplice as Hassan Ezzeddine.

When he asked Hamadi why the hijackers shot Stethem, Traugott said Hamadi replied: "This man was a Marine."

Other witnesses have also testified the hijackers apparently mistook Stethem for a U.S. Marine.

Traugott said he did not witness the shooting. "I don't think anyone saw the shooting," he said.

The former hostage said he received a telephone call four weeks ago from a man who had identified himself as "Mr. Hamadi" and said he was calling from Beirut. Traugott said the man hung up without mentioning Hamadi's trial. He did not say if he thought the call had been a threat.

Under guidelines set by the court to protect the witnesses' security, Traugott did not name his current residence. At the time of the hijacking, his address was given as Lunenburg, Mass.

Chief Judge Heiner Mueckenberger opened today's session by announcing Hamadi's parents arrived from their home in Beirut and are expected to testify Tuesday.

The court also dismissed a motion by Hamadi's defense attorneys to suspend hearing other witnesses until they have examined more evidence they say is held in the United States.

Hamadi's defenders want video and audio tapes they say are held by the FBI and the grand jury in Washington, D.C. They also want to hire an American lawyer to examine the evidence.

Hamadi was arrested at Frankfurt airport in January 1987 when customs officials found liquid explosives in his luggage.