. Last Updated: 07/27/2016

Conclusive Clues Still Elude TWA Probers

WASHINGTON -- Crash investigators' initial optimism is waning that wreckage from TWA Flight 800 will yield definitive proof of what downed the Boeing 747, and law enforcement officials now believe that if a bomb or missile destroyed the plane a case may have to be built without any conclusive physical evidence of blast damage.

After six weeks of tests, computer simulations and a partial reconstruction of the jumbo jetliner, probers have been able to reach just one definitive conclusion: the location of the blast that knocked the plane out of the sky.

They know for certain that the center fuel tank exploded, but still have no answers to the most crucial question: Why?

About 70 percent of the aircraft has been recovered from the ocean floor off Long Island so far, mostly from a few debris mounds that investigators had hoped would yield the strongest clues. Those examining the wreckage have found two tiny traces of explosive material, but say they are inconclusive.

What continues to elude them are signs of metal damage indicative of a bomb or missile blast, actual bomb parts or any evidence of a catastrophic mechanical or electrical malfunction that could have produced a spark inside the fuel tank, causing it to ignite.

Because of the lack of any metallurgy signaling sabotage or other malfeasance, the case's chief law enforcement official said in an interview last week that criminal investigators may have to wait for the discovery of additional samples of explosive residue and rely on surveillance, interviews and other intelligence work before they can declare the July 17 downing of Flight 800, in which 230 people died, a criminal act.

"Over time, more residue could get you there,'' said James Kallstrom, assistant director in charge of the FBI's New York office, which is heading the criminal investigation into the crash. "I would prefer the metal, but that is not the only thing that will get you there. You could also get there through intelligence.''

But law enforcement officials said that relying on intelligence is also risky, particularly if the focus ends up being on the subterranean world of international terrorism, and there is no guarantee it would yield a solution to the mystery of Flight 800.