Three months into the hearings of the Senate Select Committee into a Certain Maritime Incident, it is clear that they have opened a Pandora's box. There is now undeniable evidence of sustained misrepresentation in sworn testimony by high-level officials of the Commonwealth Public Service and the Australian Defence Force.

Why has this gross abuse of executive power not evoked outrage or even much interest in our Parliament and media? Partly because the details are so complicated and incremental. And partly because the key issues - what our border-protection system knew about a sinking asylum-seeker boat and why we didn't try to save it - are so confronting that our society is reluctant to face them. Our Parliament and media reflect our society. We want to think well of ourselves.

This article offers a map for some very complex terrain. We need to know about this issue, and to decide how much it matters. The committee was only accidentally empowered to investigate what Australian officials knew about the 19-metre boat that sank off Java on its way to Christmas Island on October 19, 2001, drowning 353 people and leaving only 44 survivors - a boat now known as "SIEV X" (unknown suspected illegal entry vessel). The committee was set up by Opposition parties to investigate how photographs of the navy's sea rescue of asylum-seekers on October 8 had been misrepresented as being photos of asylum-seekers throwing their children overboard the previous day, allegedly to blackmail the government into allowing them into Australia. This misrepresentation, never corrected though widely known in official circles, influenced voting behaviour in the November 10 election.

Government senators widened the terms of reference to investigate official procedure regarding the safety of asylum-seekers on all vessels trying to enter Australian waters. The purpose was to introduce evidence that even if the October 7-8 asylum-seekers had not thrown kids overboard, others had. So the original allegation would have been generally true, if not specifically true. So the defence department was told to release much previously secret information on the navy's interception of 12 asylum-seeker boats between September and December, 2001.

This data opened for scrutiny the workings of Operation Relex, the tough navy-led border-protection exercise initiated after the Tampa incident. It enabled senators to ask questions on what was known about SIEV X, and why there had been no effort to save lives. The truth was slow in emerging. It is a miracle it emerged at all. We were supposed to accept the comfortable alibi offered by Prime Minister John Howard on October 23-24, when news broke: "This boat sank in Indonesian waters. We are not responsible."

Howard's first proposition is almost certainly false. The second may or may not be true. But this is true: Two months of official testimony saw a succession of inconsistencies, shifting stories and lies. Only the recent release of summary minutes from a key interdepartmental committee exposed the extent of the cover-up.

In April, Rear Admiral Geoff Smith, head of Operation Relex, testified three times under oath that he knew nothing about SIEV X until Australia's Coastwatch organisation advised on October 22 that it was overdue, presumed sunk.

Jane Halton, chair of the whole-of-government policy co-ordinating committee in the Prime Minister's Department (the "People Smuggling Taskforce", or PST), similarly claimed that the PST had no knowledge. But on May 22, under the pressure of coming testimony from Coastwatch head Admiral Mark Bonser, Smith submitted a clarifying letter, revealing that Operation Relex had received six intelligence reports from Indonesia about SIEV X's impending or actual departure between October 14 and 22. He wrote that these reports had been considered too inconclusive to warrant an aerial search. Yet his letter noted that one report, on October 20, said the boat was small and overcrowded with more than 400 passengers.

Smith's letter repeated his April statements that the vessel had gone down in the Sunda Strait. Oddly, it noted that on October 19, when the boat sank, surveillance aircraft had been working back close to Christmas Island.

Bonser confirmed the six reports, adding their source - the Australian Federal Police. He knew of no aerial sightings of SIEV X. He suggested it could have sunk anywhere between the Sunda Strait and 80 miles south of Java in the Indian Ocean, which he confirmed was well within Operation Relex's normal air surveillance range. He confirmed Smith's April testimony that this area extended to within 30 miles of the Indonesian coast.

On June 4, incoming navy chief Admiral Chris Ritchie disclosed further intelligence reporting on SIEV X - also, he claimed, inconclusive. Contrary to Smith and Bonser, Ritchie testified that air surveillance normally took place in regular sweeps unrelated to intelligence reports, and well back from Indonesia, in the approaches to Christmas Island. So, Ritchie claimed, Operation Relex could not have seen this boat. Ritchie asserted: "It is not a SIEV, as far as we are concerned." He said there were no air surveillance photographs of SIEV X and he was unaware of any other surveillance photography of SIEV X.

On June 15, Senate-mandated publication of summary minutes from Halton's PST fatally undermined previous official testimony. It is now on public record that SIEV X had been discussed in the multi-agency PST at six successive daily meetings between October 18 and 23. These minutes show that such information was available in the defence system, and to the AFP and departments such as immigration and foreign affairs.

Many officials in member agencies, briefed by their departmental representatives at PST meetings, must have known since April that false testimony was being furnished to the committee. With the exception of Bonser, none came forward.

Even after Bonser, the system tried to sustain the claim that not enough had been known about SIEV X to warrant a search. But PST minutes of October 18 tell us that a boat was expected, in poor condition and possibly in need of rescue.

By October 22, it had a planning identifier "SIEV 8" (a number retrospectively transferred to another boat). The minutes do not make clear whether Operation Relex ever tried seriously to locate the boat, but there are a few clues.

Minutes for October 21 have the odd entry "Check Defence P3 is maintaining surveillance over Christmas Island". Why were surveillance aircraft kept so far back, if SIEV X was thought to be on its way? Minutes for October 22 note: "SIEV 8: not spotted yet, missing, grossly overloaded, no jetsam spotted, no reports from relatives." If witnesses told the truth that there was no air search, this entry may relate to tasking satellites to look for the boat. But why not our P-3 Orions?

Another mystery: Minutes of October 23 - hours before the sinking became public - report firm intelligence on the sinking and conclude: "Vessel likely to have been in international waters south of Java." Yet since October 23, Howard and defence minister Robert Hill have repeatedly said the boat sank in the Sunda Strait or in Indonesian waters - claims never backed by published evidence, but now shown to contradict the PST's own intelligence report.

There is no evidence that an Australian search was ever seriously undertaken, despite this being a sacred navy safety-of-life-at-sea obligation. It seems increasingly likely that Operation Relex did not want to risk finding this boat.

Was a cynical realpolitik decision taken - that since SIEV X was clearly too overloaded to survive the ocean journey to Christmas Island, the system should not look for it? If such a callous decision was taken, where was it taken - within the leadership of Operation Relex, or under outside political pressure?

At that time, emotions against unauthorised-entry boats were running high in Australia. Three weeks before election day, both major parties were competing to sound tougher on border protection. Might Howard's embattled caretaker government have decided that the last thing it needed was to rescue and accommodate 400 asylum-seekers from a doomed boat, not far out from Indonesia? Did they fear Labor's mockery? Could this be what the cover-up since April tried to hide?

The PST minutes are a smoking gun: they force such unwelcome questions onto the public agenda. The Canberra Times has called for an independent judicial inquiry with wide-ranging powers. But most media are still holding back - the issue may be too frightening for Australia's self-image.

If Parliament does not challenge the contempt that some official witnesses have shown for senators' interrogation, no Senate committee will ever be taken seriously by the executive or any senior official again. One does not have to be "soft on refugees" to see the importance of this precedent for the health of our democracy.

Last week, Hill cancelled today's scheduled testimony by Rear Admiral Raydon Gates, who was to have briefed the committee on his review of intelligence material related to SIEV X - a review sought by Hill. Why block Gates's testimony? It is certainly within the committee's terms of reference.

Another oddity - Smith's letter of clarification of May 22, a key document in unravelling the cover-up, was withdrawn for security clearance within an hour of tabling. It has not been officially replaced.

Does Hill - who was not defence minister when SIEV X sank - wish to help correct the cover-up, or is he trying to sustain it? This will become clearer in coming days. It will be the turn of the AFP to testify today.