WASHINGTON -- After 15 months of tests and analysis, Navy and independent scientists will present their findings in the next few weeks suggesting that the explosion that killed 47 men on the battleship USS Iowa in 1989 may have been an accident, not sabotage as the Navy believed.
New discoveries suggesting that conclusion include the existence in Navy stockpiles of a small number of gunpowder bags that are prone to ignition under extreme pressure.
The bags are used as propellant in a battleship's 16-inch guns, and the Navy had previously said it had none prone to accidental ignition.
Investigators say the new findings, gathered while they tested theories first raised by independent scientists in 1990, pose the most serious challenge to the Navy's earlier conclusion that the blast was probably an act of suicidal sabotage by a despondent young sailor.
It is not clear what action the Navy might take, although some senior Navy officers say they expect the service to reverse itself.
"It may be a month or so before there is a final decision," said Rear Adm. Brent Baker, the chief Navy spokesman.
The explosion erupted from a 16-inch gun during training exercises about 300 miles north of Puerto Rico. The blast and its investigation are one of the most turbulent chapters in Navy history.
Involved are conflicting interpretations of scientific data, veiled accusations of a homosexual lovers' affair and the Navy's reluctance to concede that a vexing problem may have no clear-cut answer.
The new technical evidence may only compound the mystery. The data offer no definitive cause of the explosion, and some of the findings are hotly contested.
But many investigators insist that the Navy can no longer rule out the possibility of an accident. "We've demonstrated a realistic probability that this could have been an accident," said one scientist, who spoke on the condition of anonymity, as did a dozen other investigators and top Navy officers interviewed.
Many top Navy officials now concede that the criminal side of the investigation, which identified Clayton M. Hartwig, a gunner's mate second class who was killed in the explosion, as the likely culprit, was flawed in its overreliance on "circumstantial evidence."
Navy investigative procedures were tightened after the case.