remains of the TWA Flight 800
remains of the TWA Flight 800Reuters

A documentary on the 1996 explosion that brought down TWA Flight 800 offers "solid proof that there was an external detonation," its co-producer told CNN on Wednesday.

"Of course, everyone knows about the eyewitness statements, but we also have corroborating information from the radar data, and the radar data shows a(n) asymmetric explosion coming out of that plane -- something that didn't happen in the official theory," Tom Stalcup told CNN.

A number of people have come forward, "all saying the same thing: that there was an external force -- not from the center wing tank, there's no evidence of that -- but there is evidence of an external explosion that brought down that plane," Stalcup said.

He cited "corroborating information from the radar data", saying that "not one single eyewitness was allowed to testify -- that's unheard of."

Asked why such information might have been suppressed, Stalcup told CNN, "That's a question that should be answered when this investigation gets reopened."

The National Transportation Safety Board acknowledged receipt of the filmmakers' petition, which was signed by a number of former investigators requesting that the investigation be reopened.

The board's investigation of TWA 800 lasted four years and "remains one of the NTSB's most extensive investigations," said board spokeswoman Kelly Nantel.

Investigators "spent an enormous amount of time reviewing, documenting and analyzing facts and data, and held a five-day public hearing to gather additional facts before determining the probable cause of the accident," she said.

Former Department of Transportation Inspector General Mary Schiavo expressed skepticism about the film's assertion.

"If this really troubled them at the time and they had this conclusive evidence -- they said they kept quiet to keep their jobs -- well, there's a duty beyond that and there's ways to report this," she told CNN. "I was the inspector general. They could have reported it to the Office of the Inspector General, to say the least. We protect whistleblowers. So, I'm very critical of them not coming forward before now if what they have is really new."

The NTSB ruled that the explosion was caused by an electrical short circuit, most likely originating in a fuel gauge line, which found its way into the center wing fuel tank, where it detonated fuel vapors and caused the B-747 to fall in pieces into the waters off Long Island.

Suspicions , however, that criminals or terrorists were behind the TWA 800 explosion have often been voiced The FBI conducted a parallel investigation, but concluded that the incident was not a crime or terrorist attack.

The evidence proves that "one or more ordnance explosions outside the aircraft caused the crash," the producers said. It does not however identify or speculate on the source of the ordnance explosions, according to CNN.

All 230 people aboard TWA 800 died when the plane, headed for Paris, exploded and crashed into the Atlantic Ocean shortly after takeoff from John F. Kennedy International Airport in New York.

Scores of witnesses observed a streak of light and a fireball, provoking suspicions that the terrorists had struck the plane with a rocket.

Investigators concluded the streak was likely burning fuel streaming from the plane's wing tank.