June 19, 2013  -- In a new documentary, former investigators who looked into the mysterious crash of TWA Flight 800, which killed 230, are breaking their silence to claim that the explosion that brought down the plane in 1996 was likely no accident, and that the final report on the cause of the blast was falsified.

TWA Flight 800 exploded in mid-air on July 17, 1996 about 11 minutes after taking off from New York's JFK airport on its way to Paris. Though theories abounded as to what happened to the plane -- from a bomb on the aircraft to it being struck by a missile or even a meteorite -- the National Transportation Safety Board concluded after a four-year investigation that the probable cause of the crash was an accidental fuel tank explosion. The NTSB said it could not be sure what exactly ignited the blast, but "of the sources evaluated by the investigation, the most likely was a short circuit outside of the [fuel tank] that allowed excessive voltage to enter it through electrical wiring..."

DOCUMENT: 2000 NTSB Report on TWA Flight 800's 1996 Crash

But according to the new documentary, named TWA Flight 800 and premiering on Epix next month, six former members of the official crash investigation have stepped forward to refute the NTSB's findings, saying the crash report was purposefully falsified, and to claim the investigation was "systematically undermined" by federal authorities.

"We didn't find any part of the airplane that indicated a mechanical failure," one of the whistleblowers says in a trailer for the film. The former officials allege the explosion came from outside the plane, though they don't speculate any further on the original source.

Another of the whistleblowers, former senior accident investigator with the NTSB Hank Hughes, said in a preview of the documentary that FBI agents were spotted on surveillance cameras going through the hanger where the crash evidence was kept "in the wee hours of the morning... for purposes unknown."

Some of the previous theories about the crash have been disproven in the years since and Tom Haueter, former director of Aviation Safety at the NTSB, told ABC News today that the former officials in the documentary are wrong. He said that the evidence that the explosion was an internal accident was "irrefutable."

There was "no sign" of penetration from the outside, Haueter said.

The whistleblowers are calling for the NTSB to reopen its investigation, and the NTSB said in a statement today it will reexamine the case if new evidence is presented or "on a showing that the Board's findings are erroneous."

"While the NTSB rarely re-investigates issues that have already been examined, our investigations are never closed and we can review any new information not previously considered by the Board," the NTSB said. "The TWA Flight 800 investigation lasted four years and remains one of the NTSB's most detailed investigations. Investigators took great care reviewing, documenting and analyzing facts and data and held a five-day hearing to gather additional facts before determining the probable cause of the accident during a two-day Board meeting."

In a petition to reconsider the accident sent to the NTSB, the former investigators and family members of the victims claim to have "new and material evidence and analysis that refute the NTSB's original findings."

But not all victims' families are on board with the new probe. Matt Zimkiewicz, who lost his sister on the flight, said in a letter to other victims' families, "It is a big distraction and particularly painful for families."

"Personal self-fulfilling motives by exploiting those who died on TWA800 is nauseating," he said. "It is my personal, as well as my family's position that we have full faith and confidence in the NTSB's final report on TWA800."

ABC News' Matt Hosford contributed to this report.