It was later discovered they had been murdered.

The case was well known in the Nambucca Valley, but few people outside of the region knew the names of the murdered children, Colleen Walker, Evelyn Greenup and Clinton Speedy-Duroux.

A new documentary from award-winning investigative journalist and filmmaker Allan Clarke, titled The Bowraville Murders, is trying to remedy this.

"How come all of Australia doesn't know the name of these victims, we hear about other similar cases all the time, but not Bowraville," Producer Dan Goldberg said.

"This is an incredible story of injustice; the families have never stopped their fight to have their voices heard, even in the face of overwhelming odds and opposition.

"The whole production was done with the support of the families; it was a huge ask for them to revisit the event and go through the traumatising events again, but they want the names out there; they don't want their children to be forgotten."

The Bowraville Murders case has received a lot of attention in the media the last few years, as the families fight tooth and nail to get justice for their children, but Mr Goldberg says, to his knowledge, the new documentary is the first instance of the whole story being told from start to finish.

"The overarching concept was to tell the stories of the family, and their ongoing battle to get justice for their children," he said.

"The documentary follows the case from the disappearance of Colleen Walker, Evelyn Greenup, and Clinton Speedy-Duroux.

"Then the reinvestigation into the murders by respected homicide detective Gary Jubelin, right up to the present day and the families attempts to get the prime suspect re-tried for the murders."

To date, there has only been one suspect in the crime who was acquitted for two of the murders. He maintains his innocence, and declined to be involved in the documentary.

The families say that the trial outcomes would have been different if the investigation had been taken seriously when Colleen Walker went missing.

Instead, most of the evidence was collected years after the fact and allegations of racism and incompetence have been levelled at police since the beginning.

Former NSW Police Commissioner Andrew Scipione famously apologised to the families of Bowraville in 2016, and agreed more could have been done when the crimes first occurred.

"As it stands, the documentary ending is quite sad; after everything the families have gone through, they still don't have closure, they still don't have justice," Mr Goldberg said.

"In the future, I hope we can revisit this story and have a happier ending, one where the families finally get justice for their children after all these years.

"None of us are going to walk away from this; we will be watching for updates and developments in this case."

The Bowraville Murders has already premiered in cinemas around Australia. Nambucca Heads Majestic Cinemas is set to screen the film on October 1 at 7pm, and SBS will show the film on September 26 at 8:30pm as part of their Australia Uncovered' series.

For more information or to find a screening near you, head over to the Bowraville Murders website at www.bowravillemurdersfilm.com.au.

"Tickets are to the premiers are selling fast, so I would encourage people to get in now," Mr Goldberg said.

"It would be easy to look away, pretend that this awful event never happened, but I encourage people to look into that fractured mirror and see what happened in the past.

"Justice is supposed to be blind, but the more we looked into this case, it became clear that's not always true, especially in the Bowraville Murders Case."

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