Much as the British authorities may deny it, Thursday's release of the only man ever convicted for the 1988 bombing of Pan Am flight 103 over Lockerbie, Scotland, suggests more clearly than ever before that justice was never done in this case - and that justice never will be done. Announcing that the cancer-stricken former Libyan intelligence officer Abdel Baset al-Megrahi would be released, days after Megrahi had conveniently dropped his second appeal against conviction, the Scottish Justice Minister Kenny MacAskill said the decision was a purely humanitarian one - made so that Megrahi would not die in a British jail. But were the authorities convinced that they had the right man - and were they convinced, more pertinently, that his conviction would have withstood the second appeal process, at which potentially embarrassing evidence pointing to a possible cover-up might have been presented - it is frankly impossible to conceive that Megrahi would have been released. You do not set free the one man convicted for the gravest single act of terrorism ever to hit Great Britain, the terrorist attack that saw more American civilians killed than any other bar 9/11, simply because he is dying. You keep such a man locked up until he draws his final breath. Two years ago, after a nearly four-year study, the Scottish Criminal Cases Review Commission finally granted Megrahi the right to mount a second appeal - a decision based on half-a-dozen possible grounds for a miscarriage of justice. By setting Megrahi free now, the British authorities are ensuring that any such miscarriage will not be definitively exposed. Critically, the widely held belief that it was Iran, and not Libya, that orchestrated the Lockerbie bombing, and that it was carried out by the Syrian-hosted Popular Front for the Liberation of Palestine-General Command, will not be put to renewed legal test. Conspiracy theories have ebbed and flowed throughout the 21 years since the Lockerbie bombing. But the most dominant and credible of those theories, tellingly, is the explanation that the investigators themselves advanced and followed for the first weeks and months after the blast. As I reported from London in The Jerusalem Post just weeks after the bombing, the investigators were convinced that the bomb that brought down Flight 103, killing 270 people, had been concealed in a Toshiba radio-cassette recorder - a bomb highly similar to four devices that had been found in the possession of members of the PFLP-GC arrested in a Frankfurt suburb just weeks before. The cell was said to have been planning attacks on airplanes heading to the US and Israel; the bombs it had built were detonated by a barometric pressure device and timer, designed to activate when a plane reached a certain altitude. It was reported that a fifth bomb had been built and had disappeared - presumably the bomb that blew up Flight 103. It was also reported at the time that American intelligence had established that the PFLP-GC had been paid $10 million by Iran to carry out the Lockerbie bombing. Iran's presumed motive: to avenge the downing, by the US Navy's guided-missile cruiser USS Vincennes, of an Iran Air Airbus in the Persian Gulf five months before Lockerbie, in which all 290 passengers and crew were killed. The US said it had mistaken the civilian airliner for a fighter jet; Iran said the attack was deliberate and vowed revenge; Ayatollah Khomeini promised the skies would "rain blood." Libya's purported culpability, by contrast, has generally been presented in the context of its various mid-1980s confrontations with the United States - notably Libya's bombing of a Berlin nightclub used by US troops, and US air attacks on targets in Benghazi and Tripoli in 1986, including a strike on the personal quarters of Col. Muammar Gaddafi in which his adopted daughter was killed. Libya originally gave up Megrahi for trial - along with Lamin Khalifah Fhimah, the Libyan airlines' station manager at Malta's Luqa Airport, where the prosecution alleged that the suitcase containing the Lockerbie bomb began its journey - after years of resistance and consequent UN sanctions. It then paid compensation to the Lockerbie victims' families as a condition for the lifting of those sanctions, which had cost it an estimated $30 billion. But Fhimah was acquitted, Gaddafi savaged the Scottish judges when they found Megrahi guilty, Libya never formally accepted specific responsibility for the bombing, and in 2004, its prime minister told the BBC that it had capitulated only because "we thought it was easier for us to buy peace." Those who claim that the Lockerbie investigation was deliberately skewed, to incriminate Libya and clear Iran and Syria, often link the purported cover-up to the first Gulf War. The US-led coalition, gearing up to take on Saddam Hussein, needed Syria to stay out of the conflict and did not want to irritate Iran, they argue. Libya was just a scapegoat. The notion that the British and American governments would be prepared to mount so extensive a cover-up seems inconceivable. It should be noted that most of those killed on Flight 103 were Americans. But as Hans Koechler, who was appointed by the UN Security Council to serve as an observer throughout the Lockerbie legal proceedings, told me two years ago, the authorities in the UK, in Scotland, plainly did not want a full investigation. "Only a child could believe that a lone intelligence officer could have planned and carried out Lockerbie. Yet they have not looked for others." Perhaps the most troubling aspect of a possible Lockerbie cover-up is the suspicion that, if the true culprits were never tracked down and will never be prosecuted, they and their government sponsors have felt free to orchestrate further murderous outrages. That is the bitter, lasting concern given the highly unsatisfactory conclusion to the Lockerbie affair produced by the canceling of Megrahi's appeal and his compassionate release on Thursday. Almost certainly now, we will not know if Lockerbie represents a monstrous miscarriage of justice, and if the true perpetrators were left free to strike again. But we will suspect it.