Sydney – It's been 30 years since five Australia-based newsmen were gunned down in the East Timorese border town of Balibo. It's been 30 years since their bodies were dragged into a room, doused in petrol and set alight.

And for the families of the dead, it's been 30 years of heartache, and of grappling with the mystery of what really happened on October 16, 1975. With a coronial inquest due to start early next year, that vexed question may finally be answered.

The Balibo Five, as they've since come to be known – Greg Shackleton, Gary Cunningham and Tony Stewart of Channel Seven, and Malcolm Rennie and Brian Peters of Channel Nine – were in East Timor to document Indonesia's invasion of the tiny nation.

Indonesia denied there was an invasion. So the newsmen travelled to Balibo, to the frontline, eager to expose the truth. Indonesian special forces troops entered the town and within an hour the newsmen were dead.

Official reports, both Indonesian and Australian, claim the men were caught and killed in crossfire. But eyewitnesses say there was no battle for Balibo and, therefore, no crossfire to get caught in. Many now believe the men were deliberately murdered.

But questions persist: If the men were murdered, who ordered it? Were the men targeted because their footage might expose the truth about the invasion? What did the Australian government know, and when? Was there a cover-up? What really happened to the men's remains?

There have been two Australian inquiries into the deaths, in 1996 and 1999, conducted by government-appointed former National Crime Authority chairman Tom Sherman. Both times, Mr Sherman upheld the view that the men were killed in crossfire.

But the Sherman inquiries were widely dismissed as inadequate and lacking in scope, and the families of the dead continued to demand that a full judicial inquest be conducted.

Their wish was granted in June this year when NSW State Coroner John Abernethy agreed to hold an inquest into the death of one of the five, Brian Peters, at the request of Peters' sister, Maureen Tolfree. Peters was a British citizen, working at the time of his death as a cameraman for Channel Nine based in Sydney.

Ms Tolfree, now 60, has spent half her life battling to uncover the truth surrounding her "fun-loving and adventurous" brother's death. It's become her crusade, and it's overtaken her life.

"It's just the staggering injustice – that's what eats you up inside. So I just kept on and on and in the end someone listened to me in Australia," Ms Tolfree told AAP from her home in Bristol, England.

"I'd never thought we'd get this far – I was quite shocked when the coroner's court agreed to proceed with the case – I thought the Australian government would put the blocks on it, I thought something would stop it happening."

Ms Tolfree hopes something will come of the inquest to assuage her anguish. "I still miss Brian to this day, I think about him all the time – he was such a character, he was unforgettable," she said. "It has taken over my life – all my money has been spent on campaigning, trying to find the truth... My marriage broke up over it because I was so obsessed with finding out, and my health's suffered too – I've had a couple of heart attacks through the stress."

Counsel for Ms Tolfree, Robert Dubler, said the inquest will undoubtedly uncover new information.

Mr Abernethy has said he will not consider any political events surrounding Mr Peters' death, but would look at whether the cameraman "was in fact murdered and, if so, by whom".

Mr Dubler said the inquest would be different from the Sherman inquiries because the coroner has the power to compel witnesses and compel the obtaining of documents.

"Whilst no-one would suggest that Sherman did anything but an honest and proper job, many people thought that it did not appear to be independent, to have the commonwealth choose an officer to conduct the inquiry," Mr Dubler said.

Mr Sherman only spoke to those witnesses who were willing to speak to him, and no Indonesians were required to give evidence or answer questions, he said.

If the inquest does uncover compelling evidence about who was responsible for the deaths it is extremely unlikely the killers will actually be brought to justice.

Ms Tolfree's solicitor, Rodney Lewis, said some of the facts surrounding the incident would probably be exposed for the first time. "(But) the prospect of getting charges to stick, for a warrant to issue, for a person to be arrested, for a person to be extradited, then for a person to be tried and convicted... yes, that's remote," Mr Lewis conceded.

Already there have been setbacks. Last month a key witness to the killings died of kidney failure. Olandino Maia Guterres, who entered Balibo with the Indonesian troops that day, claimed in 1998 that former Indonesian information minister Yunus Yosfiah issued the order to kill the newsmen after they filmed the attack on Balibo. He told the ABC's Foreign Correspondent program that Yosfiah, then a captain of the special forces, gave the order to shoot the men as they tried to surrender.

The United Nations Temporary Administration for East Timor (UNTAET) investigated Olandino's allegation and concluded there was enough evidence to charge Yosfiah, but could not secure his extradition.

Ms Tolfree, who spoke at length with Mr Guterres, said his testimony left her with no doubt that Yosfiah was behind the murders. "That man murdered my brother," she said. "There were certain things Olandino told me that make me certain he saw what happened, and certain Yosfiah is to blame."

But Ms Tolfree also is not optimistic the inquest will result in Yosfiah's capture, much less a conviction. "I don't think so, no," she said. "Like I said, I really just want the truth told."