TWA INVESTIGATORS CHECKING OTHER AIR CRASHES FOR CLUES.

Byline: Matthew Purdy The New York Times

Federal officials investigating the crash of Trans World Airlines Flight 800 said Monday that they were making a detailed comparison of foreign air crashes caused by bombs in their search for information that could help them prove their theory that the Boeing 747 was brought down by a bomb.

Although the officials said they were not ready to declare the crash a result of a criminal act, they are comparing the evidence gathered in the TWA crash to the 1988 bombing of Pan Am Flight 103 over Lockerbie, Scotland, the 1989 downing of a French airliner over Chad and a 1985 crash of an Air India airliner that was blamed on a bomb.

The federal officials said they are consulting foreign investigators and examining material from those earlier crashes as a way of testing the theory that the Paris-bound 747 was bombed.

Robert Francis, the vice chairman of the National Transportation Safety Board, who is heading the investigation, said: ``Certainly, I think we've acknowledged from the beginning that there's a possibility that this could have been an act that would be comparable to those. And we're doing what we would do in any accident investigation and that is comparing the things that have similarities.''

For the first time Monday, officials publicly said that the catastrophic event that apparently broke the airplane in two, whether caused by an explosion or a mechanical malfunction, occurred near the front of the airplane. Joseph Cantamessa Jr., the special agent in charge of the FBI's New York office, said the bodies of victims sitting near the front of the plane showed more severe injuries, indicating they ``experienced the bulk of the significant event.''

Officials have said that the front part of the plane apparently separated from the rest of the plane and plunged into the Atlantic Ocean before the rest of the aircraft.

Investigators said they were one piece of evidence away from declaring the crash a criminal act, but that evidence continued to elude them Monday.

Divers continued pulling large pieces of wreckage from the ocean off Long Island on Monday, and preliminary tests on some of them showed traces of explosives. But for those pieces, and others pulled up in previous days, more sophisticated testing at the FBI laboratory in Washington failed to confirm the early positive tests.

In addition, investigators said Monday afternoon, metal that at first seemed to bear a pockmarked pattern consistent with an explosion, turned out to have been marred by having been submerged in the ocean.

Officials also said that the final loud noise picked up by the airplane's cockpit voice recorder just before it stopped working on the night of the crash would not alone provide enough evidence for investigators to determine the nature of the cataclysmic event.

``We're all a little frustrated by not being able to find the cause of this occurrence,'' Cantamessa said.

The TWA flight crashed the day after a French magistrate left Libya, where he had been investigating the 1989 bombing of a DC-10 over the Sahara Desert. All 170 people on board that plane were killed.

The French Transport Ministry said shortly after the French jet went down seven years ago that information from the plane's data recorders ``showed that the flight proceeded in a normal manner until a total interruption, which translates as an explosion in flight.''

``The work of the crew was proceeding normally when the recording of words and electronic data abruptly stopped,'' the statement said.

The Associated Press reported three days after the 1989 accident that investigators had found evidence of explosives on board. The AP also reported that a plane flying the same flight had been bombed on the ground in N'Djamena, Chad, in 1984.

Reuters reported last year that France planned to try four Libyan suspects in absentia, including a brother-in-law of Col. Moammar Gadhafi, Abdallah Senoussi. The report quoted lawyers familiar with the case as saying that Libya had refused to turn over the suspects to French officials.

On July 18, the day after the TWA flight exploded en route to Paris, Reuters quoted a spokesman for the French Foreign Ministry as saying that the magistrate, Judge Jean-Louis Bruguiere ``was received cordially by the Libyan judicial authorities.''

A senior American intelligence official said Monday night that the United States had no evidence of any connection between the TWA crash and the pursuit of suspects by French authorities in the Chad bombing.