A LONG-running conspiracy theory about the death of NSW bushranger Captain Thunderbolt was fabricated, historians say.
The outlaw Frederick Wordsworth Ward, popularly known as Captain Thunderbolt, was shot dead by police at Uralla, New England, in May 1870.
But a book released in 2009, titled Thunderbolt: Scourge of the Ranges, suggested that police shot the wrong man and Thunderbolt escaped to live out his final days in America.
It says that the government hid the truth from the public for 140 years.
Historians David Roberts and Carol Baxter at the University of New England say the facts tell a different story.
"The documents are pretty straightforward and uncomplicated," Dr Roberts told AAP.
"They show that this guy was shot, he was brought in, he was identified unequivocally by various experts, and he was buried.
"Historians would never say that there was more to the story."
Dr Roberts said there was no evidence that the outlaw had lived on. "We don't know that he might not have escaped to America unless we do DNA testing on his grave.
"But to come with a wild conspiracy or counter history, you need some reasonable grounds for making that argument. Otherwise you're just telling stories to the gullible.
"It's entirely made up."
At the time of the book's release, author James Hamilton with Barry Sinclair said the NSW government had hidden documents that would prove their theory.
"There are no secret or hidden documents," Dr Roberts said.
"In fact there are no reasonable grounds for suspecting that these documents might exist.
"What the authors have essentially done is, they've created this entirely fantasised story."
Dr Roberts said locals still talked about the Thunderbolt conspiracy and he hoped his research would set the record straight.
"There's a lot of the old farmers around the place still think that Thunderbolt escaped," he said.
"The way (the book) was promoted in the media here has led everybody to universally suspect that this is a true story.
"What we're doing is basically laying it out in pretty plain terms."
The paper by Roberts and Baxter will be published in March in the International Australian Studies Association's Journal of Australian Studies.
A documentary-drama on the controversy, titled Empty Grave: the Thunderbolt Mystery, will also be released this year.