The National Transportation Safety Board (NTSB) has denied a petition to reconsider its findings in the investigation of the 1996 crash of TWA Flight 800.

On July 17, 1996, the Boeing 747-100 exploded and crashed into the Atlantic Ocean shortly after takeoff during a flight from New York JFK to Rome, killing all 230 people on board.

Although sabotage was initially suspected, NTSB concluded that a fuel tank explosion—sparked by a short circuit in the wiring—caused the crash.

In 2005, FAA  issued a directive requiring airlines to reduce flammability levels in jet transports. Since then, FAA said it has issued 283 directives to prevent the ignition of vapors in and around commercial aircraft fuel tanks.

In June 2013, a group called The TWA 800 Project filed the petition to reopen the case, claiming a “detonation or high-velocity explosion” caused the crash.

“Our investigations are never ‘closed,’” NTSB acting chairman Christopher Hart said. “We always remain open to the presentation of new evidence.”

Before responding to the petition, NTSB said its staff met with the petitioners’ representatives and listened to an eyewitness who described what he saw on the night of the accident. After a thorough review of all the information provided by the petitioners, NTSB said it “denied the petition in its entirety because the evidence and analysis presented did not show the original findings were incorrect.”