For a fourth frustrating day, federal officials searching the tossing waters of the Atlantic Ocean off Long Island were unable to reach the wreckage of TWA Flight 800 on Sunday, leading them to worry that the investigation could take far longer than they originally thought.
Efforts to locate the Boeing 747's debris were unsuccessful, even though Coast Guard vessels had crisscrossed the 500-square-mile grid more than 100 times by mid-afternoon. As a result, divers were not sent into the water Sunday.
With the crucial evidence _ the shattered wreckage _ lying, unlocated, under 120 feet of water, federal investigators still could not officially declare what they deeply believe: that the explosion was the result of a criminal act.
"We'll be lucky if we get this in 11 days," a federal investigator said. Less than 1 percent of the wreckage has been recovered. And as wind and sea shifted the evidence on the ocean bottom, investigators worried that critical pieces might be washed away or lost under mounds of sand.
A crucial piece of equipment, the side-scanning sonar, snagged on something on the ocean floor Sunday and now has to be retrieved, federal officials said.
Then a video camera sent below to look around failed to work. So, investigators said, they were not even sure if the signal they picked up Friday indicating a 15-foot object on the ocean floor was, indeed, the trail of debris they thought it was.
"It could be anything," acknowledged Al Dickenson, the chief investigator for the National Transportation Safety Board.
"We did not move the ball in terms of finding the wreckage," added James Kallstrom, the FBI agent in charge of the criminal investigation. He added, though, that his agents had questioned "thousands" of people and had made progress in building possible strategies for further investigation. He did not elaborate.
Early Sunday, federal investigators reported that a Navy ship had picked up a "ping" sound, presumably from the black box that is a central object of the search. They said the sound was faint and faded in and out.
Later in the day _ after the Navy reported its equipment problems _ Navy officers said they had heard no pings. The conflicting accounts could not be resolved.
Once the debris is located, a priority will be to check the four engines of the Boeing 747 for any damage that might indicate that a catastrophic mechanical failure was at fault in the crash Wednesday, rather than an explosive device.
The searchers did find another body on Sunday, the first since Thursday morning. With 101 bodies accounted for, that leaves most of the 230 passengers and crew aboard the doomed plane still in the waters of Moriches Bay.
By evening, 46 of the bodies in the Suffolk County medical examiner's office had been identified. Families, bitter over the slow pace of recovering and identifying the bodies, met Sunday evening with the medical examiner, Dr. Charles Wetlin.
But, even as authorities waited for the hard forensic evidence of the metal fragments from the airplane, investigators on the Joint Terrorism Task Force were interviewing witnesses and pursuing possible leads on all fronts.
On the one hand, they dispatched federal agents to Athens, the plane's last stop before it flew to Kennedy Airport. Presumably they are in Greece to check on the passengers who boarded the plane there, and the cargo loaded there, pursuing one of the theories: that the plane was brought down by a bomb.
At the same time, investigators said they were investigating a report of a stolen boat, though they did not say precisely where or when it had been reported missing.
This, they said, could support the possibility that a missile was fired at the plane from offshore. If a surface-to-air missile was fired at the plane, it would have been from a boat, they said, explaining that the plane was too far from shore for a small missile to reach it.
Investigators said they were still taking this theory as seriously as any of the others because they have interviewed 10 witnesses in various locations _ some who were in boats, others who were on shore or in other air lanes _ who have recalled seeing something streaking toward the plane before it exploded.