For more than four decades, Thelma Collins has carried the burden of her brother's murder alone. Every night since his death in May 1964 at the age of 19, she said a prayer to her 'baby brother in heaven', told him about her day, perhaps shed a tear or two, then quietly got on with her own life raising a young family. Her 12 children never knew that their uncle was Henry Hezekiah Dee, one of two black teenagers tied to a tree by members of the Ku Klux Klan, beaten unconscious with tree branches then thrown into the Mississippi River to drown. 'I wanted to give them full, happy lives without having the worry of any of this,' reasons Mrs Collins, now a 70-year-old grandmother with heart problems living in a tiny town in Louisiana. 'I thought about Henry and about what happened every day, and I still cry about it, but it's something I never talked about with my children.' She admits she had long since given up any hope of ever seeing her brother's killers brought to justice. All that changed in January when reputed former Klansman James Ford Seale, 71, was charged with abducting, beating and murdering Dee and his friend, Charles Moore, 43 years ago, one of several prominent unsolved crimes from the Deep South during America's civil rights era. In 2005, Moore's older brother, Thomas, and a Canadian television journalist discovered Seale alive and well and living in Mississippi despite his family's claims that he had died years previously. Although the FBI reopened their investigation, Seale remained openly dismissive of any suggestion he could be held to account for the boys' deaths. 'I ain't in jail, am I?' he once spat at reporters. But on April 16, Seale is scheduled to stand trial at the US District Court in Jackson, Mississippi, the latest of a growing number of ageing defendants called to account for their alleged racist actions decades ago. He is likely to spend the rest of his life in jail if found guilty. His story is a familiar one to those who remember one of the darkest periods in America's chequered history of race relations, the era of burning crosses, lynchings, bomb attacks on African-American churches and homes, and hooded Klansmen roaming the countryside at will, attacking blacks and destroying their property. According to the indictment, Seale and fellow Klan members who have since died wrongly convinced themselves that Dee and Moore were smuggling guns into southern Mississippi. They are said to have snatched the young men from a rural roadside while they were hitchhiking and beat a confession out of them before dumping them in the river to die, weighed down by chains and parts of the engine from an old pick-up truck. Their bodies were not found for two months. Jurors will hear the evidence of Ernest Gilbert, a former Klansman-turned-FBI informant who told investigators that Seale's now-dead brother had implicated him in the crime. Charles Edwards, an alleged accomplice of Seale on the day of the murders, is also expected to testify against him. A conviction, Mrs Collins says, would help close a long and painful chapter of her life and, although she knows the trial will provoke some distressing memories, it will allow her brother to finally be at rest. 'I believe he'd be happy about it,' she said. 'Justice should be served.' Seale's trial, however, will take on a much wider significance. The high-profile court case will be the first involving an alleged former Klansman since Alberto Gonzalez, the US attorney general, announced in February that the FBI and Justice Department were to look again at almost 100 cold-case murders from 11 southern states during the 1950s and 1960s suspected of being racially motivated. 'The wounds they left are deep and may never be healed, but to those individuals who have lived with guilty consciences for years, we say you haven't got away with anything, we are still on your heels,' Mr Gonzalez said. 'We would much prefer, of course, that justice had been served more than 40 years ago in this case. But what we are doing, bringing closure to this horrible crime by trying this case through a public trial, should serve as notice to those who would violate the civil rights of their fellow citizens. 'Not every case will be resolved. In many cases the persons may already be dead or it may be established that there is no federal jurisdiction, but these cases belong on our radar. We hope that we can bring closure to some of them.' As in the case of Seale, several of the crimes were investigated when they first happened. Charges, however, were often dropped or, on the rare occasions they did reach a courtroom, defendants were quickly acquitted by all-white juries. Similarly, many of the outrages were committed by, or with the blessing of, law enforcement officers. Seale himself was a former sheriff's deputy who, according to FBI documents from the time, cheerfully admitted his involvement in private but who knew he was likely to escape justice as long as he kept quiet when it mattered. Federal agents, overworked at the time by the search for three missing civil rights workers in the Mississippi Burning murder investigation - the most notorious racial crime of that era, which was later made into a film - handed Seale's case to local authorities and a judge promptly dismissed all charges against him. Richard Cohen, president of the Alabama-based Southern Poverty Law Centre, says there are dozens of cases like Seale's waiting to be resolved. The civil rights advocacy group has published a list of 76 men and women who died between 1952 and 1968, all thought to be the victims of racial killings. Among them are Isadore Banks, whose burned corpse was found tied to a tree in Marion, Arkansas, in 1954; Mattie Green, of Ringgold, Georgia, whose home was bombed in 1960, and Willie Joe Sanford, who drowned in Hawkinsville, Georgia, in 1957 when his naked body was tied to undergrowth. There are also victims of the authorities. The white jailers who beat William Owens, a second world war veteran, to death in a North Carolina prison in 1956 were never arrested. Nor was the police officer who shot dead Larry Bolden, an unarmed black teenager, on a Tennessee street two years later. 'These are murder cases from the civil rights era that still cry out for justice, cases that cry out for further investigation,' Mr Cohen says. 'Some people would rather see that era forgotten but to me the argument that we shouldn't reopen old wounds and that it's time to move on is perverse. We aren't just talking about individual injustices, they are cases where the entire criminal justice system was perverted.' At face value, it might appear to some that the United States has suddenly become swept up in some righteous wave of public atonement, determined to make amends for the wrongs done by some of its citizens in years gone by. Just two weeks ago the state of Maryland followed the lead set by its neighbour Virginia in February in issuing a formal apology for its role in the slave trade. But some experts say it is also symptomatic of the declining influence of the Ku Klux Klan and a desire to bring closure for at least some victims or their families before those involved are dead. 'The Klan doesn't have any meaningful political power any more and is no longer able to intimidate or sway any jury in the way it once could,' says Rick Ross, director of the New Jersey-based institute of the same name that monitors hate groups and cults within the US. 'Its membership has waned, its cultural influence has ebbed and the only interesting footnote is that it has tried to use the immigration crisis in the US as a focus for recruitment. 'These cases are about tying up the loose ends of a dying movement and bringing people to justice before they are deceased.' Mr Cohen, meanwhile, points proudly to the recent successful convictions in a number of prominent civil rights era cases. In 2001, Thomas Blanton and Bobby Frank Cherry were found guilty of the 1963 bombing of the 16th Street Baptist Church in Birmingham, Alabama, which killed four young girls. And two years ago former Klansman Edgar Ray Killen was convicted of the Mississippi Burning case killings and sentenced to three 20-year sentences at the age of 80. 'There's still a deep reservoir of residual racism in the Deep South, and the people bear the legacy of the scars of segregation, in health care, employment, housing and so on,' he says. 'So the strides that we have made are amazing. We shouldn't be satisfied with where we are but we shouldn't forget how far we've come.' As for Mrs Collins, she has waited 43 years to see her brother's killer in court and, once the case is over, hopes that only the happy memories remain. 'I don't have any photographs of Henry but it's all up here in my mind,' she says. 'I'll always remember him as a happy, quiet boy. He never thought they'd hurt him, he was always more worried about his grandmother.'