Caroline Overington – There is a scene in the new Australian film Balibo that is so sickening in its violence that it is almost unbearable to watch. Five Australian journalists – from Channel Seven and Channel Nine – have gone to Balibo, near the East Timorese border with Indonesia, on the eve of the 1975 invasion.

They've gone deliberately to Balibo. Everybody knows it's dangerous, but they want vision of the Indonesian army, coming over the hills. The journalists are dressed in civilian clothes – Stubbies, short-sleeved shirts and floppy hats – and are carrying camera gear.

They do get some footage of the invasion as it begins, but then get caught in the house where they had been staying.

They raise their hands in the universally recognised symbol of surrender. They plead their case, as Australians, and as reporters. What happens next is so barbaric that people at pre-screenings of the film have cried out.

Later, they wondered, could that possibly be true? After all, Balibo is not a documentary, it's a movie, but based on a solid foundation of historical data, of cables and documents, of reports and eyewitness testimony.

The film-makers – director Robert Connolly and his co-writer David Williamson – employed a consulting historian, Clinton Fernandes, of the University of NSW, who is perhaps Australia's leading scholar on East Timor.

Fernandes is based at the UNSW's Australian Defence Force Academy campus in Canberra. He is a graduate of the Royal Military College, Duntroon and spent 13 years in the armed forces including several years as an intelligence analyst on East Timor.

With his help, the Balibo film-makers have established a website, where it's possible to search, scene by scene, for the historical documents that support the events shown.

For example, there is a scene in which reporter Roger East (played with enormous passion by Anthony LaPaglia) is sitting on a wharf, eating fish and chips wrapped in newspaper. Look closely, and you can see the newspaper has a photograph of Indonesian president Suharto and Australian prime minister Gough Whitlam.

The film uses an exact copy of the original newspaper. Labor had come to power in the 1972 elections, and Australia-Indonesia relations were running smoothly. Whitlam is known to have discussed East Timor with Suharto on two occasions in September 1974 in Yogyakarta, Indonesia, and in April 1975 in Townsville.

Fernandes sourced three official cables, that prove, he says, "Indonesia informed the Australian government in advance about its plan to invade East Timor, and that the Australian government went along with the pretence".

In another scene, the film shows a man, apparently Indonesian, ordering the murder of the five journalists in Balibo. On the Balibo website, Fernandes explains that this character is Dading Kalbuadi, the overall commander of the Indonesian forces in East Timor.

"His dress in the film is based on his actual clothing from that time," Fernandes says. "In truth, he was not at Balibo during the killing of the journalists; he was in his tactical headquarters approximately 10km away. He flew in by helicopter immediately after Balibo had been captured."

The film shows him at the site of the killings because that is the best way to show the audience what a Sydney coroner concluded in 2007, that "there is strong circumstantial evidence that colonel Dading Kalbuadi gave orders to his field commanders that anyone found in Balibo was to be killed, including the five journalists".

Fernandes says that Kalbuadi "was aware that the journalists were at Balibo and did not want them to obtain film footage of the Indonesian invasion. They were killed in a deliberate act to prevent them from revealing the truth."

Besides compiling historical documents to back each scene in the film, Fernandes spent several days discussing "history and nothing else" with LaPaglia, as he prepared for his role as Roger East, known as the sixth reporter to die in the invasion. He was shot in Dili several weeks after the Balibo five were killed.

"Every paper I gave him to read, came back to me with blue marks, blue ink and underline, and questions," he says. "I am an academic and I do not know any other actors. Perhaps wrongly, I had formed an impression that perhaps not all actors are serious people, but he was a very serious person.

"I have seen newspaper reports saying, oh, when he was in East Timor, he played soccer with the East Timorese children. I can assure you, he did much more than that. He worked and he studied and he applied himself in a way that was extremely impressive."

Fernandes has seen the film in several of its incarnations since last November.

"Every time I've seen it, it's more and more disciplined, and it's now very disciplined. Everything you see is accurate. They are so accurate that even the pistol that you see fired at the end by the guy in the safari suit is the actual model, Browning high-powered 9mm pistol, that was used.

"The photographs I used were taken in Dili, the morning after the invasion, by people who were there, so the safari suits you see, they are based on the real safari suits.

"I got my hands on all of that stuff, and gave such detail to the costume people that I thought they might start to think I was a bit pedantic, but they came back, and they actually did it.

"For me, as a historian, there's always a risk when you get involved in a commercial venture, that the film will be good and my reputation will be destroyed and other historians will laugh at me, and this has not happened."

If there is something missing from the film, it's the role played by the Australian government and, in particular, Whitlam and his ambassador to Indonesia, Richard Woolcott.

Woolcott does not appear in the film and Fernandes says "and I suppose it would have been a different film, if that had been the subject" but on the website, there are three original cables that make it clear that Australia was given confidential information by Indonesia "that they are going to attack Balibo, and the person who is writing those cables is Richard Woolcott. He has to pretend we don't know, publicly, but privately, the government knows."

Former defence minister Bill Morrison told the Sydney inquest into the death of the Balibo five in 2007 that he did not tell Whitlam about the murders in Balibo because "he had enough problems on his hands".

In his book, The Hot Seat: Reflections on Diplomacy from Stalin's Death to the Bali Bombings, Woolcott says he did not know the Australians were in Balibo, and he learned of their deaths from ABC radio on October 17, 1975.

"At that time of civil war and Indonesian clandestine involvement we simply did not know at the embassy that there were any Australians in the Balibo area," Woolcott's memoir says.

It is understood that Woolcott may have seen the film. LaPaglia believes he saw him at a Q&A in Melbourne, after the official launch. "He did not speak. But he was there," LaPaglia says.

The Australian attempted to reach Woolcott at both his Sydney and Canberra homes yesterday, but was not successful. Of the invasion, Fernandes says Woolcott has said "well, you have to be pragmatic [in diplomatic relations], but in fact, that argument fails on all grounds, because it becomes impossible for Australia to have a mature relationship with Indonesia if Australia is being asked to cover-up for Indonesia".

LaPaglia, who attended a screening of Balibo at News Limited's headquarters yesterday, says he prepared for his role as the reporter East – who dies after being dragged across the wharf, his hands tied with wire – by reading the 1996 Sherman report, the 1999 review of the Sherman report, and the coroner's report of 2007.

Like Fernandes, LaPaglia says Balibo is accurate, "except, perhaps, that the reality [of the killings of Australians and East Timorese] was much worse. You can't show some of the things that happened."

East Timor's President Jose Ramos Horta, too, says the reality was worse. "One journalist in particular, was tortured," he says.

Ramos Horta is portrayed in the film as a man fiercely committed to East Timor and its people; he's shown sleeping on dirt floors, woken by the sound of a rooster, dressed in fatigues, with calf-length combat boots.

It has long been known that he left Timor three days before the invasion, to plead his people's case before the UN. In the film, he offers East a seat on the last plane out, before the killings begin, but East declines, and dies terribly.

Ramos Horta was 24 years in exile, living in New York and in Sydney, lobbying foreign governments and the UN. In 1996 he was jointly awarded the Nobel Peace Prize with Carlos Belo, the leader of East Timor's majority Catholic population.

Romas Horta says it is true that East went to East Timor at his urging and he says East's murder in Dili, was "almost 100 per cent accurate, and that it's true that he refused to leave, when told to go".

The film shows an ABC journalist Tony Maniaty meeting the Channel Seven crew of Greg Shackleton, Gary Cunningham and Tony Stewart informing them that it was dangerous to travel to Balibo.

The coroner concluded that the journalists themselves were responsible for being alone in Balibo, noting that journalists enjoy no greater protection from attack than other civilians.

In his history of the final days, Fernandes says the attack on Balibo "began with heavy artillery bombardment from the ships off Batugade at dawn around 4am on October 16, 1975". It was accompanied by mortar fire from the surrounding hills.

Three of the journalists were filming. They were told to go but decided to hang on because they were determined to get evidence that Indonesia invaded unprovoked, Fernandes says.

"The attack was launched from three directions. One company entered from the Maliana road, another from the Cova road while Team Susi led by Yunus Yosfiah was in the forefront of the middle force.

"Four journalists emerged from a house with their hands in the air in a gesture of surrender. They were all wearing civilian clothing. Brian Peters was in front of the others.

"The journalists were not mistaken for combatants. In addition, they clearly identified themselves as Australians and as journalists."

After the murders, "the five corpses were dressed in military uniforms, guns placed beside them, and photographs taken in an attempt to portray them as legitimate targets".

Some have questioned the wisdom of the journalists, for travelling to Balibo at that time, but not Ramos Horta. "They were not in the wrong place at the wrong time," he says. "They were in the right place at the right time."