THE EGYPTIAN government objected to transferring jurisdiction over the investigation of the EgyptAir crash from the National Transportation Safety Board (NTSB) to the FBI, but that has not deterred the bureau from playing a major role in the probe. That is as it should be. With preliminary evidence from the flight data recorder and cockpit voice recorder indicating nothing mechanically wrong with Flight 990, the logical course is to investigate the human dimensions of the tragedy vigorously.

It may turn out that some yet-undetected mechanical failure brought down the EgyptAir flight. All conceivable explanations must be fully examined, including the possibility that some time after takeoff, someone -- perhaps one of the pilots -- intentionally pushed the Boeing 767 into a dive. What will not do are attempts by authorities on both sides of the Atlantic to push theories about what occurred on the night of Oct. 31 that do not comport with evidence collected to date.

The NTSB, which remains officially in charge of the investigation, was right to criticize speculation about what might have caused the crash -- speculation based on partially analyzed data. A prayer in Arabic provides insufficient basis to conclude that the crash was deliberate. Likewise, Egyptian authorities should be willing to issue similar cautions against unfounded, speculative conclusions being uttered on their side. To contend, as some have in Egypt, that the fatal crash was caused by laser rays or sabotage by Israel's Mossad intelligence service or a U.S. government plot designed to avoid exposing Boeing to liability is inflammatory as well as absurd. As recently as last week, a senior Egyptian transportation ministry official, Gen. Issam Ahmed, suggested, without supporting evidence, that the crash was caused by an explosion in the plane's tail section.

The doomed aircraft took 217 passengers and crew members to their deaths in the Atlantic. Away from the microphones and press, American and Egyptian technicians and investigators are working cooperatively and painstakingly to find out why. That is where the focus belongs.