Sirhan Sirhan, assassin of Robert F.Kennedy, launches new campaign for freedom 42 years later

They say the new material hands them "game, set and match" in their campaign to release him from the life sentence he was given on being convicted for gunning down the senator at a California hotel.

They have launched a fresh appeal on behalf of Sirhan, 67, claiming in court for the first time that prosecutors fabricated ballistics evidence against him at trial, switching a bullet that was taken from the dead senator's neck for one that they claimed matched the defendant's gun.

Lawyers also seek a re-examination of claims that Sirhan was framed by shadowy agents - indirectly suggested as being the CIA - who they say "hypno-programmed" him into taking part in the shooting to divert attention from their own fatal gunfire.

Court documents filed in federal court in Los Angeles now pull together years of research, evidentiary documents and psychological analyses of Sirhan for a case that his lawyer says proves him as a victim of "an egregious miscarriage of justice" and "horrendous violations" of his legal rights.

"On the law, and on the evidence, it's game set and match to us. It's all over," Dr William Pepper told The Sunday Telegraph.

"But we are dealing with a high profile political assassination that involves the government and government agencies and a cover-up for 43 years, So I'm not confident that we are going to overcome the politics, but I'm confident that they have got to give us an evidentiary hearing and put all this under oath in a court of law, which has never happened."

Senator Kennedy died on June 6, 1968, one day after the shooting at the Ambassador Hotel in Los Angeles, where he had been celebrating victory in the California primary of the race for the Democratic presidential nomination. He had just delivered his victory address in the ballroom and was taking a short cut out of the hotel through the crowded kitchen when Sirhan stepped forward and opened fire.

The senator's loss altered the course of American politics and sent shock waves through a country still coming to terms with the assassination four and a half years earlier of his brother, President John F Kennedy, by political malcontent Lee Harvey Oswald.

At trial in 1969, Sirhan - a Palestinian Christian refugee - was asked by his defence counsel, Grant Cooper, whether he had shot Senator Kennedy. "Yes sir," he replied, echoing admissions made in police custody directly after the incident.

"Do you doubt you shot him?" Mr Cooper demanded. "No sir, I don't," Sirhan responded, launching into a diatribe about US policy in the Middle East and later stating that he resented Senator Kennedy's support for Israel.

"RFK must die - RFK must be killed," he wrote in a notebook prior to the shooting.

But despite multiple confessions, insists Dr Pepper, Sirhan did not shoot Senator Kennedy. Chief among the new evidence he has put forward is a claim that prosecutors switched bullets in evidence, to incriminate him.

When the coroner, Dr Thomas Noguchi, removed a bullet from the politician's neck during a post-mortem examination, he marked it with the handwritten reference "TN31". Yet on an inventory of the exhibits that were presented in court during Sirhan's 1969 trial, the bullet - suggested by prosecutors to match Sirhan's .22-calibre Iver-Johnson Cadet revolver - is referenced "DWTN".

"Those markings showed that the bullet they put into evidence was different to the one Noguchi, the medical examiner, removed from Kennedy's neck," said Dr Pepper. "This was a fraud perpetrated on the court. Under the law they should set aside the verdict and re-try Sirhan or set him free."

Other evidence that defence lawyers believe now qualifies for re-examination by the court are witness statements that place Sirhan in front of Senator Kennedy at the time of the shooting, when medical evidence has shown that he was shot from behind.

Detailed technical analysis of the only audio recording made of the shooting is also contained in the latest appeals documents, backing claims that there were 13 or more shots fired at the scene when Sirhan's weapon was capable of firing only eight.

Using forensic techniques not available in the 1960s and described in court documents as being "light years ahead of listening to the tape with the human ear," Philip Van Praag, an Arizona-based audio engineer and computer technologist, concluded that there were many shots fired, from more than one gun.

Analaysis of the soundwaves and vibrations "revealed a frequency anomaly with respect to five of the shots, indicating that a second gun was fired, of a make and model different from that which (Sirhan) fired".

Mr Van Praag's report also concluded: "In the pantry, (Sirhan) was firing from east to west, whilst another gun was firing five shots from west to east."

Sirhan's defence has previously attempted to claim that he was a victim of sinister mind-control by unidentified agents who programmed him to shoot under hypnosis. It is now renewing that claim, based on studies of Sirhan by Dr Daniel Brown of Harvard University, a specialist in trauma memory and hypnosis, who dismisses the notion that the convicted assassin is, or ever was, schizophrenic as "blatantly wrong."

Sirhan was "an involuntary participant in the crimes being committed because he was subjected to sophisticated hypno programming and memory implantation techniques which rendered him unable to consciously control his thoughts and actions at the time the crimes were being committed," the new court petition states.

Files compiled by the FBI and the Los Angeles Police Department corroborate some of the details of Sirhan's claim that he was manipulated by a third party, Dr Brown adds. For example, Sirhan recalled under questioning by Dr Brown that he was taken to a police firing range and shown by the range master how to shoot at vital organs on human targets.

"He also described a man with a turned down moustache and foreign accent who first introduced to him the idea of killing government officials.

"Months after the Petitioner (Sirhan) recalled these details, I found an entry in the police file that corroborated the petitioner's free recall. The entry showed that not only did such a firing range exist, but that petitioner visited that police firing range and signed the register just days before the assassination.

"He was accompanied by a man with a turned down moustache and a foreign accent. The man refused to identify himself or sign the register," Dr Brown stated.

Conspiracy theorists have for years sought to debunk the theory that Sirhan was a lone, crazed assassin with a personal and political vendetta, theorising that Senator Kennedy was targeted by the CIA or others because he was set to win the Democratic nomination for president, posing a threat to expected Republican nominee Richard Nixon and - as an anti-war candidate - raising the prospect of pulling the US out of the war in Vietnam.

Alternative "suspects" they have suggested include a unidentified lady in a polka-dot dress, seen by two witnesses, said to have stood next to Sirhan before he fired and to have shouted "We shot him" as she fled, and an Ambassador Hotel security guard.

Sirhan is now incarcerated at Pleasant Valley State Prison in Coalinga, California, a grim 640-acre facility that in the time that he has been there has experienced riots, escapes, hunger strikes, a murder, stabbings and shootings.

He is housed alone in a single cell but is being considered for transfer to a shared cell, where his notoriety could put him at risk. "If they move him, we have to be concerned that he stays alive. People can get killed. The idea of double-celling does concern us," said his lawyer.

Sirhan has said for some years that he now remembers nothing of Senator Kennedy's shooting, and he is said to appreciate that there will be public cynicism over his claims. "People can say 'Boy, it's all rather fantastic. Yes, it's fantastic. But it's true," insisted Dr Pepper, acknowledging that critics will point out his client's multiple confessions as proof of guilt.

"He understands all that. At the time, he was convinced he did it. Everyone around him said, 'You did it.' Even his own lawyer at the time said, 'We're not going to defend you, we're going to save your life,' because he faced the death sentence. When you are surrounded by people who tell you that you did it, you think you did."

Professor Laurie Levenson, director of the Centre for Ethical Advocacy at Loyola Law School, Los Angeles, who has examined the Sirhan case - including interviewing witnesses to the shooting - said: "I don't think many people in the legal community are taking this latest challenge that seriously.

"There have been many challenges and many questions unanswered, but the whole crypto-programming theory isn't one that's well received. And the switching of the bullet... people have always been concerned about the physical handling of the evidence, but I doubt that will be the smoking gun that will show there was a conspiracy."

Just as the assassination of Senator Kennedy's brother John has prompted decades of conspiracy theories, Sirhan's case is unlikely ever to rest, she said.

"Some cases never die and when you shoot a Kennedy that's definitely the case. But I think the public has stopped caring. It's been decades and frankly even in my classes I don't think many people know who Sirhan is.

"I take it seriously because I hope we have not imprisoned a man for over 40 years for a crime he didn't commit, but I don't think there are a lot of people in the criminal justice system who feel this latest attempt will answer all the questions. The longer the time lapse, the more suspicious are these new theories."