Painful history ... Lindy Chamberlain with Azaria at Uluru. From the outset, there was the question of motive. For all the world the couple were paragons of virtue, Michael a pastor in the Seventh-Day Adventist Church, a respectable, if not widely understood Christian denomination, and Lindy, daughter of a Seventh-Day Adventist pastor. There was nothing in their background to suggest any inclination to criminality. There was nothing wrong at all, except that the Chamberlains, like most people, might have had an anthropocentric view of themselves. They had the notion, which comes from the Bible, that man has sovereignty over the world's creatures, and that other creatures defer, or should defer, to them. Despite repeated instances of animals demonstrating they don't give a fig for the idea, it still comes as a shock when it happens. After Azaria's disappearance and the flurry of publicity, things quickly started going belly-up. The mistakes started with the decision of Constable Frank Morris to move the baby's jumpsuit to check inside for human remains before photographing it, when it was found at the base of Uluru - then known as Ayers Rock - a week after the baby disappeared. Partly because the "crime scene" was in the wilderness, there was insufficient effort to preserve physical items, in particular the groundsheet in the tent where traces of dingo paw prints might have been found. Deficiencies in the police forensic performance were remarked on by the first coroner, Denis Barritt, in February 1981 when he found a dingo had taken the baby and severely criticised some police and the public for adopting what he thought was a prejudiced view. When the case was reinvestigated later in 1981, the world-renowned forensic pathologist Professor James Cameron examined the bloodied jumpsuit. He used spectrophotometry to discern what he decided was the bloodied handprint of a young adult on the jumpsuit. It certainly was a handprint. But it was not blood. It was dust - therefore the suggestion that Lindy, after cutting the baby's throat, held the jumpsuit in her bloodied hand was entirely unjustifiable. Cameron's report to the Northern Territory government also theorised that because of the circumferential bleeding at the collar the baby's throat had been cut and she had been decapitated. Justice Trevor Morling, the royal commissioner who inquired into the case in 1986-87, referred to the possibility of post-mortem bleeding as an explanation for the bloodstains on the jumpsuit, a possibility not mentioned in Cameron's report.

A long road to the truth ... Michael and Lindy Chamberlain during the Morling royal commission in 1986. If Cameron's report did the damage, causing the territory to reopen the inquiry, the total failure of the forensic biologist Joy Kuhl, who decided that matter taken from the Chamberlains' car and possessions was blood, was a catastrophe. Not only that, she performed tests that indicated the "blood" contained foetal haemoglobin, meaning it came from a baby. As it turned out in the royal commission, there was no blood. She had mistaken a positive response to tests for the presumptive presence of blood to mean she had found blood. She had fallen into the same trap as Cameron. She assumed that other explanations for the presumptive presence of blood could be dismissed. Professor Malcolm Chaikin, a renowned textiles expert, was called to examine abrasions in the baby's jumpsuit to see whether they had been caused by scissors or another bladed instrument, an important question because of the suggestion someone might have cut the jumpsuit to fabricate a dingo attack. He said the presence of tufts in the jumpsuit was the surest evidence a bladed instrument had been used. After the Chamberlains' convictions, a group of amateur scientists demonstrated with a domestic dog that canine dentition could produce perfect tufts, but Chaikin dismissed what they tried to put to him. He used an electron spectrometer on the jumpsuit to demonstrate that the tufts of ruptured fabric were in "planar array", meaning a bladed instrument must have been used. But he could never get away from what he had initially said about tufts. There has been a lot of talk about whether an unbiased jury could have been found, and about Australians' intolerance of outsiders, even about possible motives by the territory government to challenge a finding of a dingo attack because of an adverse effect on tourism. But most of the blame has to be placed squarely on the shoulders of the key scientific witnesses for the Crown. They were too sure of themselves and most unwilling to concede, along with some of the police, that they might have been wrong.

Dr Kenneth Brown, a forensic odontologist, was not satisfied that the first coroner's report was the final answer and he believed further investigation was required. He consulted Cameron, who was his mentor, to ask where he himself had gone wrong in his initial investigations. The Northern Territory police, stung by Barritt's criticisms, were happy to see the case reopened. In the second inquest, under coroner Gerry Galvin, when the tide had turned against the Chamberlains, they referred to Barritt as ''Ding-a-Ling Dennis". There was eventually intense hostility to this reporter because in my reporting for the Herald I took what was seen as a pro-Chamberlain stance. At one point I felt compelled to ring the office of the chief minister to complain. When the convictions came under increasing scrutiny from a wide spectrum, including federal MPs, the territory government continued to stand fast and insist the Chamberlains had been found guilty after a fair trial. No one in the territory government relished seeing Lindy in jail, and confidential negotiations were conducted with the Chamberlains' solicitor, Stuart Tipple, over a possible pardon for her. That came unstuck when news of the approach leaked. In 1985, when I was in the territory interviewing the chief minister, Ian Tuxworth, his media adviser said that any agitation in the south would only delay a release. "Any agitation down there, it is in for another six months," he said. Tuxworth agreed. The passion for the territory government to insist that things happen according to established procedure continued even after it relented in 1986 and ordered a royal commission. But trying to preserve the convictions became increasingly difficult once the Morling royal commission got under way. When it shot so many holes in the Crown case on identification of blood, the territory's Crown counsel tried to suggest the baby had been killed outside the car. Morling said the Crown had started in the car and that was where it had to finish.

When the Chamberlains were exonerated in 1987, the territory retained Michael Adams, QC, to resist the application. The Crown witnesses in the trial were forced by the adversary system into stubbornly upholding their opinions. As it turned out years later, some of them were wrong. That was an obstacle for the Chamberlains. So was the attitude of the government and police, who were pushed by political pressure into the same defensive posture. The weight of police and Crown resources, backed by the financial resources of a government, could be crushing to a couple like the Chamberlains. In the initial period, they could not overcome it. Now, after more than 30 years, they finally have. Malcolm Brown has been covering the Chamberlain case since September 1980.