More than 75 years after 35 people were killed in the Hindenburg air disaster, experts believe they finally know what caused the crash.
The Hindenburg hydrogen-filled airship was preparing to land at Lakehurst, New Jersey, on May 6, 1937, when it exploded and plunged to the ground in flames.
After the disaster, investigators concluded that a spark had ignited leaking hydrogen gas but they were unable to agree on what caused the spark, or the leaking gas.
Numerous conspiracy theories also surfaced as the cause of the accident remained unsolved.
Researchers at the South West Research Institute in the US have conducted experiments on models to show that static electricity may have caused the crash, The Independent reports.
The team at the South West Research Institute, led by British aeronautical engineer Jem Stransfield, worked to rule out theories by blowing up or setting fire to model airships built to scale.
They also studied old footage of the accident and eyewitness accounts.
In a documentary to be broadcast in the UK this week, the researchers reveal the sequence of events they believe unfolded prior to the crash.
"I think the most likely mechanism for providing the spark is electrostatic," Mr Stransfield told The Independent.
"That starts at the top (of the ship), then the flames from our experiments would’ve probably tracked down the centre.
"With an explosive mixture of gas, that gave the 'whoomph' when it got to the bottom."