Rupert Cornwell: Leonard Peltier: brutal cop killer, political prisoner, or symbol of a defeated people?

It was back in Moscow more than 20 years ago, when I was covering the Soviet Union for this newspaper, that I first heard the name of Leonard Peltier. President Reagan would come to town and lecture the Kremlin – entirely justifiably – on its abysmal human rights record. And each time the Russians would accuse the US of hypocrisy and ask, what about Leonard Peltier, America's own human rights prisoner?

Just recently, I heard his name again. Peltier, a Lakota Indian, has now served more than 32 years of two consecutive life sentences imposed for the murder of two FBI agents during a shoot-out at the Pine Ridge Indian reservation in South Dakota in 1975. He denies carrying out the killings, claiming he is simply another victim of the systematic persecution and crushing of the native American peoples carried out by the United States. Next Tuesday, he will have his first full parole hearing since 1993, and once more his supporters are mobilising.

Over the years, these have been many and famous: among them, naturally, the former Soviet leader Mikhail Gorbachev, as well as Pope John Paul II, Nelson Mandela, the actor Robert Redford, the European Parliament, various national legislatures in Europe, a former UN commissioner for human rights and Amnesty International. Amnesty does not classify Peltier as a prisoner of conscience, but it too is urging that parole be granted, because of doubts about whether his trial was fair and whether political factors played a part in his conviction.

The FBI will have none of this. For US law enforcement, Peltier was, and remains, nothing more than a particularly brutal murderer, who dispatched two of its own men execution-style as they lay wounded and helpless. But whatever precisely happened that summer day long ago, one thing is undeniable. Leonard Peltier is a player in the continuing tragedy of native Americans.

He was an activist in the American Indian Movement (AIM), founded to mark the 100th anniversary of the 1868 Fort Laramie treaty that supposedly guaranteed Lakota ownership of the sacred Black Hills in South Dakota, which were then seized by the US government after the Black Hills gold rush. In its quest to reassert the rights of native Americans, AIM was also inspired by the Black Power movement of African Americans that was gaining momentum at that time; and the Pine Ridge reservation, where the infamous Wounded Knee massacre of 1890 took place, became a focal point of its campaign.

In 1973, the movement staged a two-month takeover of the Wounded Knee site, ended only by the dispatch of police and US army units to regain control. There followed two bloody years during which AIM was hounded by the US government and so-called "progressive" Indians, readier to assimilate into white American society, and Pine Ridge boasted the highest murder rate in country.

The climax came on the hot summer afternoon of 26 June 1975, when two FBI agents entered the reservation to serve an arrest warrant on a young native American named Jimmy Eagle, suspected of kidnap. Peltier and two AIM comrades, Robert Robideau and Dino Butler, believed, however, that the agents were seeking them. A gunfight ensued in which the FBI men were pinned down, wounded, and finally killed with shots to the head at point-blank range.

Immediately the authorities launched a massive murder hunt for Eagle and the other three. Eventually, murder charges against Eagle were dropped, while Robideau and Butler were caught and tried by a federal court, only to be acquitted on the grounds that they acted in self-defence. Peltier, who had fled to Canada, would face the wrath and vengeance of the FBI on his own.

A year later he was seized by the Mounties after a tip-off and extradited to the US, where in 1977 he was tried and convicted. But to this day, controversy persists. In its zeal to nail Peltier, the FBI has been accused of intimidating witnesses to secure evidence, first for the extradition, and then the conviction. Ballistics evidence that might have exculpated him was allegedly withheld. There is no doubt Peltier was among those who fired some of the shots at the agents, but it has never been established who actually killed them.

The trial itself, Peltier's supporters insist, was tilted unfairly against the defendant. The jury of 10 men and two women was all white, while the judge barred all testimony on the conditions at Pine Ridge before the fatal day – thus reducing chances of the self-defence acquittal secured by Robideau and Butler.

After six hours of deliberation, the jury found Peltier guilty on both counts. But in a final statement before sentencing he declared: "I'm not the guilty one here. White racist America is the criminal, for the destruction of our lands and our people." And although successive appeals courts upheld the verdict, that was the version of the Peltier story seized upon by the Soviets in the 1980s, as some small counterweight to the horror stories of KGB persecution, forced exile, psychiatric hospitals and the rest.

The Soviet Union is long gone, but the Peltier case never quite disappeared. Over the years, parole applications and demands for a retrial have been unfailingly dismissed. But the FBI was sufficiently alarmed at rumours that Bill Clinton was considering a grant of executive clemency when he left office in January 2001 that 500 agents and their families staged a demonstration in protest outside the White House.

This time, too, you'd have to bet against parole – despite the three long decades Peltier has been behind bars, despite a recent beating when he was transferred to a new prison, despite his poor health. Never has he expressed any remorse for the deaths of the two agents, in which at the very least he played a role. Instead, in all likelihood, he will remain a prisoner of a country he hates, a futile but poignant symbol of a defeated, broken people.