In 1968, nearly five years after the assassination of President John F. Kennedy, his younger brother Bobby was shot dead as he sought nomination as the Democrats’ presidential candidate. On Saturday, our serialisation of a gripping new book revealed why its authors are convinced the man jailed for 50 years for his murder couldn’t have done it. Today, they provide compelling evidence that the CIA was behind the shooting...

Once he was safely behind bars, the man who’d apparently shot Senator Robert F. Kennedy proved surprisingly co-operative. In the eight months leading up to his trial in 1969, Sirhan Sirhan patiently answered all the questions put to him by a battalion of psychologists and psychiatrists. All except two.

He didn’t know why he’d shot Bobby Kennedy. And he had no recollection of anything he’d seen or done in the hours leading up to the assassination, or even of pulling out his gun.

His amnesia seemed to be genuine — and inexplicable. So, in a final bid to unlock his frozen mind, an eminent psychologist was asked to put him into a hypnotic trance.

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Murdered: Bobby Kennedy lies dying at the Ambassador Hotel in LA after being shot in 1968

Dr Bernard Diamond, a professor of psychology, law and criminology, found 25-year-old Sirhan very easy to hypnotise, though he still remembered nothing about shooting Kennedy in the early hours of June 5, 1968 at the Ambassador Hotel in Los Angeles.

The professor eventually decided to prompt him under hypnosis to re-live the event. So, in January 1969, he began by taking him ‘step by step’ through the hours leading up to the murder.

Under hypnosis, Sirhan described having four Tom Collins cocktails at the hotel before walking to his car with the intention of driving home. Realising he was drunk, he’d changed his mind and returned to the hotel for a coffee.

There, he met a girl in a polka-dot dress, who was also looking for coffee. He didn’t know her name, but remembered finding her sexy.

In 1969, Sirhan Sirhan - the man who’d apparently shot Senator Robert F. Kennedy - was put under hypnosis and described meeting a girl in a polka dot dress in the hours leading up to the murder. Elayn Neal (above) has been identified by eyewitnesses as that elusive girl

Next, Diamond told Sirhan that he was back in the hotel pantry. Kennedy had just given a victory speech, having won the Democratic primary that took him a step closer to running for President. And now the Senator was walking through the hotel pantry, accompanied by aides …

‘Who was with you when you shot him?’ asked the professor.

Sirhan wrote on a piece of paper: ‘Girl, the girl, the girl.’

His only other recollection was of being choked by someone on a table in the pantry. This had indeed taken place: one of the men escorting Kennedy had grabbed him in a headlock to try to stop him pumping out more bullets.

But Sirhan couldn’t recall shooting the Senator. Nor could he remember ever writing anything about wanting to kill him.

This also struck Diamond as strange. Not long after the shooting, police had found a notebook at Sirhan’s home, in which he’d written: ‘RFK must die. RFK must be killed. Robert F. Kennedy must be assassinated.’

Still in a trance, Sirhan started making scribbles on the paper. When asked why he was doing this, he wrote: ‘Practice, practice, practice, practice, practice.’

‘Practice for what?’ asked the professor.

‘Mind control, mind control, mind control, mind control,’ wrote Sirhan.

Dr Bernard Diamond, a professor of psychology, law and criminology, found 25-year-old Sirhan (above) very easy to hypnotise, though he still remembered nothing about shooting Kennedy in the early hours of June 5, 1968 at the Ambassador Hotel in Los Angeles

‘Who was with you when you shot him?’ asked the professor. Sirhan wrote on a piece of paper: ‘Girl, the girl, the girl.’ His only other recollection was of being choked by someone on a table in the pantry. This had indeed taken place: one of the men escorting Kennedy had grabbed him in a headlock to try to stop him pumping out more bullets

Diamond wasn’t sure what to make of this. Above all, he was puzzled by the fact that whenever Sirhan came out of a trance, he was unable to remember anything about the shooting.

At further sessions, Diamond used a technique called ‘post-hypnotic suggestion’ to implant instructions in Sirhan’s mind.

‘I said: “You’re asleep now, and when you wake up I’m going to take my handkerchief out... And you are going to feel that you’re going to climb around the bars [of the cell] like a monkey,”,’ he recalled.

This worked like a dream. As soon as Diamond took out his handkerchief, Sirhan ‘started climbing up the bars of the cell all the way to the ceiling and perched himself up there’.

Afterwards, he had no memory of either being hypnotised or performing a monkey routine.

To Diamond, the strength of Sirhan’s memory blockage, together with the ease with which he could be put into a trance, suggested only one possibility. Before shooting at Kennedy, he must have undergone previous — and much deeper — hypno programming.

‘In his conscious mind, there was no awareness of such a plan, or that he, Sirhan, was to be the instrument of assassination,’ said Diamond. ‘The mirrors in the hotel lobby, the flashing lights, the general confusion — this was like pressing the button which starts [a] computer.’ Above, Sirhan Sirhan is arrested at the scene of the assassination

But who could have done it? The professor concluded that Sirhan had hypnotised himself, using mirrors and candles. On the night of the assassination, he theorised, the camera lights and mirrors in the Ambassador Hotel must have triggered a trance.

And then, for whatever deeply buried reason, he’d pulled out his gun and shot Senator Kennedy.

‘In his conscious mind, there was no awareness of such a plan, or that he, Sirhan, was to be the instrument of assassination,’ said Diamond. ‘The mirrors in the hotel lobby, the flashing lights, the general confusion — this was like pressing the button which starts [a] computer.’

Professor Diamond was fully aware that most people would think he’d strayed into the realms of science fiction. Indeed, when he took the witness stand at Sirhan’s trial, he told the jury: ‘I agree that this is an absurd and preposterous story, unlikely and incredible. However, these are the psychiatric findings in this case.

‘They are absurd, preposterous, unlikely and incredible because the crime itself was a tragically absurd and preposterous event, unlikely and incredible.

‘But I am satisfied that this is how Sirhan Bishara Sirhan came to kill Senator Robert F. Kennedy on June 5, 1968.’

The jury evidently shared Diamond’s pessimistic assessment of his own diagnosis: they found Sirhan guilty of murder.

Yet his theory had been largely correct. Before apparently committing the crime that sent shockwaves round the globe, Sirhan Sirhan had almost certainly been hypnotised.

Unknown to the professor, however, just one organisation possessed the necessary know-how to make an ordinary man commit an act of extreme violence — and remember nothing about it. And that, as we shall see, was the CIA…

So who was the girl in the polka-dot dress? While under hypnosis, Sirhan had recalled meeting her just before the shooting, so she was clearly worth tracing.

In fact, the police had been flooded with sightings of a young white woman in a black and white polka-dot dress.

Twenty-five eyewitnesses at the Ambassador Hotel had mentioned her in their statements — and 13 of them had reported seeing her with a man matching Sirhan’s description.

So, within hours of arresting Sirhan, police started hunting for Miss Polka-Dot. Then, a few weeks later, they abruptly abandoned the investigation.

The search for his female accomplice, they announced, had been a wild-goose chase. She was merely a mirage — invented by an ‘overwrought’ 20-year-old Kennedy campaign worker.

But there was far more to the story than the police were prepared to admit.

The allegedly ‘overwrought’ campaign worker was Sandy Serrano. On the evening in question, which was very hot, she’d stepped out onto one of the hotel’s external staircases to cool off. It was sometime after 11.30pm.

Five minutes later, Sandy saw two young men and one woman walking towards her up the stairway. As they passed her, the woman said: ‘Excuse me.’

Sandy noticed that one of the men — thought to be Sirhan —looked as if he needed a haircut. The other was Mexican-American, clad in a gold-coloured sweater. And the dark-haired woman was about 5ft 6in, and wearing a white dress with black polka-dots.

Both went into the Embassy Room, where Kennedy was about to give his victory speech, and Sandy thought no more about them. Then, half an hour or so later, the girl and one of the men rushed back to the staircase.

The girl in the polka-dot dress ‘practically stepped on me’, Sandy Serrano told detectives. ‘And she said: “We’ve shot him. We’ve shot him.” ‘Then I said: “Who did you shoot?”

Elayn Neal's husband, Jerry Capehart, told his son that he'd worked for the CIA — ‘on mind-control experimentation’ - in the Sixties. Did the CIA programme Sirhan Sirhan to kill Bobby Kennedy (above)? The short answer is that there’s no definitive proof of agency involvement

‘And she said: “We shot Senator Kennedy.”

‘And I says: “Oh, sure.” And she came running down the stairs and the boy in the gold sweater came running down after her.’

Startled and upset, Sandy then ran into the Ambassador Room, asking everyone she met if it was true that Kennedy had been shot. People looked at her blankly, unaware that elsewhere in the building, he’d just taken a bullet in his brain.

Five minutes later, Sandy found her flatmate Irene Chavez in a hallway outside the Ambassador Room. In a police interview, Irene later recalled that her friend was crying as she told her about ‘seeing a man and a woman run down the stairway where she’d been sitting. The woman said something about they had shot Kennedy’.

Immediately after speaking to Irene, Sandy ran to a payphone and called her parents in Ohio. They, too, would later tell police that she was crying.

Meanwhile, the first police officer to respond to a radio alert about the shooting had arrived at the hotel. As he came in, he was approached by an elderly couple with a story remarkably similar to Sandy’s.

As the officer duly noted, the elderly couple ‘were on the balcony outside the Embassy Room when a young couple, early 20s, came running from the direction of the Embassy Room shouting: “We shot him, we shot him.” When asked who, the young couple replied: “Kennedy, we shot him.”’

The old couple’s names later disappeared from police files.

Sandy was later interviewed again by the homicide division. The only detail she could add was that the polka-dot girl had a ‘funny nose, turned up like a pixie’.

Police also interviewed Vincent DiPierro, a student, who’d been watching the polka-dot girl in the moments before Bobby was shot. She’d caught his eye when she came into the hotel pantry, he said, because she was ‘very shapely’.

With her was a young man — Sirhan — who climbed onto a tray stacker. According to DiPierro, the girl was ‘almost holding him’.

Sirhan said something and turned to look at her ‘with a stupid smile’. The girl just smiled in response. After that, everything happened very fast.

‘I thought he was going to go and shake [Bobby’s] hand,’ said DiPierro. ‘And then he kind of swung around and he went up on his tiptoes and he shot.’

Another witness, who’d also been in the pantry, reported that immediately after the shooting, he’d seen a man and a girl in a white dress fleeing through a side corridor. He’d tried to pursue them, but there were too many people in the way.

Others could also testify that Sirhan had been with the girl in the pantry. And there were also simply too many near-identical sightings of them with the man in the gold sweater to be dismissed as mere coincidence.

Was she perhaps a Kennedy aide? Unlikely. Conrad Seim, a 50-year-old press photographer, said that the polka-dot girl had approached him twice that evening, asking to borrow his Press pass.

He’d refused. But she’d somehow got into the Embassy Room anyway — because another witness recalled seeing her without a pass and wondering how she’d got in.

In a thorough police investigation, all these eyewitness accounts should have strongly suggested that Sirhan was not alone on the night of June 4-5. Yet the search for the polka-dot girl was quietly abandoned.

Some witnesses were told that they’d been mistaken. Others were dismissed as phonies or unreliable. As for Sandy, the police asked her to take a lie-detector test.

These are meant to take place in an atmosphere of complete calm — which is crucial for accurate results. A transcript of the test, however, shows that the interviewer was hectoring and brutal, accusing Sandy among other things of ‘shaming’ Kennedy with her lies, which must have left her unable to sleep at night.

Predictably, Sandy — who was reduced to tears — failed the test. Two days later, the police called off their search for the polka-dot girl and announced that Sandy Serrano had invented the entire story.

Today, however, she still insists that she told the truth.

Genuine conspiracies happen. Watergate was a conspiracy. And it’s undoubtedly true that the CIA engaged in a succession of very real conspiracies, such as attempting to assassinate dictators and masterminding coups d’etats.

So maybe we shouldn’t be too surprised to learn that the CIA also launched a top-secret project to turn ordinary men into robot-assassins.

Millions of dollars were spent on the project during the Fifties and Sixties. Then, in 1973, in one of his final acts as director of the CIA, Richard Helms ordered the destruction of all records relating to what the agency referred to as ‘Artichoke’.

By accident, however, several boxes containing records of the agency’s mind-control experiments have survived. And these reveal that the CIA conducted hundreds of experiments with hypnosis, at first using its own staff as volunteers.

‘Can we create by post-H[ypnosis] control an action contrary to an individual’s basic moral principles?’ reads one CIA memo. ‘Could we seize a subject and in the space of an hour or two by post-H control have him crash an airplane, wreck a train, etc?’

Another memo reports that hypnotised volunteers had been able to produce ‘automatic writing’. After being awakened, they’d ‘been amazed and startled’ by what they’d written.

Even more pertinent to Sirhan’s case was an experiment involving two CIA secretaries. Both were hypnotised, then one was sent to sleep while the other was ordered to fly into a rage and shoot the sleeper dead with a pistol.

These instructions were carried out to the letter, though happily the pistol wasn’t loaded. And neither woman could recall a thing when they woke up.

Project Artichoke had worked: the CIA now knew how to create hypno-programmed assassins who’d later be unable to recall their actions.

In 1969, while at San Quentin State Prison, Sirhan Sirhan was examined by the jail’s psychologist.

Dr Eduard Simson met him regularly and concluded that far from being a lone and politically motivated assassin, Sirhan had been hypno-programmed to be a distraction.

‘He was put up to draw attention while experts did the work,’ said the psychologist. ‘He would be easily blamed. He was programmed to be there.’

And Simson swore under oath: ‘Sirhan’s trial was, and will be remembered as, the psychiatric blunder of the century.’

In 1997, America’s leading expert on hypnosis, Dr Herbert Spiegel, reviewed the case. In a sworn affidavit, he noted that Sirhan could be programmed to carry out crazy actions — such as behaving like a monkey.

The speed at which he could be put into a trance, he said, suggested he’d been hypnotised before the assassination. And it was also telling that Sirhan had an automatic tendency to repress any memory of being hypnotised.

This, of course, precisely echoed the aims of Project Artichoke.

In 2008, Sirhan’s lawyers asked Dr Daniel Brown — another world-authority on hypnosis — to investigate their client. His work with Sirhan would go on for eight years. Finally, he began to unlock more of Sirhan’s memories under hypnosis — and again they centred on the girl in the polka-dot dress.

That evening in 1968, she’d overheard him asking a bartender for coffee and started talking to him. They could get coffee in the room behind the platform where Kennedy was speaking, she said.

There, they discovered a large silver coffee urn. As they flirted over their coffee, Sirhan decided he wanted to have sex with the girl later.

They were interrupted by an official who told them they couldn’t remain in the room for security reasons and should move on to the hotel kitchen.

Sirhan then recalled what happened next. ‘I followed her. She led — I was like a little puppy after her. She went straight to that pantry area — with my being so attracted to her, I was just glued to her.

‘As we were coming in [to the pantry], I’m still sleepy, very sleepy. The place was darkish, a deep place to get romantic with that girl.

‘Then she sat up on the table with her back to the wall. I am just looking at her, trying to take her beauty in. I am trying to figure out how to hit on her. That’s all I can think about.

‘All of a sudden, she’s looking over my head. Then she taps me or pinches me. It’s startling, like when you’re stuck with a pin. She says: “Look, look, look.”

‘I turn around. There are people coming through the doors. I am still puzzled about what she is directing me to. Then all of a sudden, she gets more animated.

‘She put her arm on my shoulder. Then I was back at the target range — a flashback to the shooting range.

‘I thought I was at the range more than I was actually shooting at any person, let alone Bobby Kennedy. Then everything gets blurry.’

To Dr Brown, these recollections pointed to an entirely logical conclusion.

The way the girl touched Sirhan, he said, was ‘suggestive of the kind of mind-control done in that era’ — in other words, her touch had triggered the hallucination that he was merely practising his target shooting.

‘It is my opinion,’ stated Dr Brown firmly, ‘that Mr Sirhan did not act under his own volition and knowledge or intention at the time of the assassination.’

And the girl in that polka-dot dress? Over the past 50 years, a succession of researchers has assembled a long list of possible candidates, but none could identify her.

And then, last year, my co-author Brad finally traced her.

He’d started the quest by tracking down seven surviving eyewitnesses and asking them to look at a photographic line-up of possible contenders.

Among the 12 photos, he included one of a woman whose family had contacted one of Kennedy’s aides, but who’d never been publicly associated with the day of the shooting.

It wouldn’t be her, thought Brad, but he added her picture just to make up the numbers.

To his astonishment, each of the seven witnesses independently picked her as the closest match to the girl in the polka-dot dress. Her name was Elayn Neal, and she’d died five years before.

After contacting her family, Brad discovered that she’d married in 1966 but used to disappear from home, without explanation, for long periods.

Her children recalled that she’d always seemed haunted by something, and often expressed fears that she was being followed.

They also talked about her obsession with a white dress with black polka-dots, which she’d often take out of storage just to look at it.

But it was only after her death that a nephew wrote to one of Bobby Kennedy’s aides, enclosing a photo of Elayn and asking if she could possibly have been the girl in the polka-dot dress. The aide had then asked Brad to investigate further.

So, after all seven eyewitnesses apparently recognised Elayn, he dug a little deeper. Her husband, Jerry Capehart, he discovered, had refused to let her wear the polka-dot dress, and this had caused explosive rows between them.

But the most spine-chilling discovery of all was what Capehart had done for a living in the Sixties. Just before his own death, he’d told his son that he’d worked for the CIA — ‘on mind-control experimentation’.

Did the CIA programme Sirhan Sirhan to kill Bobby Kennedy? The short answer is that there’s no definitive proof of agency involvement.

However, it’s a matter of record that, as one-time U.S. Attorney General, Kennedy had clashed with both the FBI and CIA. It’s also a matter of historical record that there was a long and dishonourable history of co-operation between organised crime and the CIA, including joint attempts at political assassination.

One of the most powerful mobsters at the time was Jimmy Hoffa, leader of the Teamsters Union and a sworn enemy of Bobby Kennedy. He was serving an eight-year jail sentence for jury tampering and attempted bribery and a concurrent sentence for fraud at the time of the assassination.

Two weeks after the killing, a former prison inmate contacted police to report a conversation he’d overheard the year before. Hoffa, who was talking to two friends, had apparently said: ‘I have a contract out on Kennedy and if he ever gets in the primaries or ever gets elected, the contract will be fulfilled within six months.’

And Hoffa’s name came up again in the hours after the assassination. A woman had walked into the LA County Sheriff’s office to report a conversation with Hoffa’s son. If Kennedy were elected president, he told her, he’d be ‘rubbed out’.

Does this prove that the CIA plotted with mobsters to murder the man thought by many to be on his way to the White House? No, it does not.

But we believe that there are strong grounds to suggest that the assassination was the result of a conspiracy.

It’s now overwhelmingly likely that Sirhan was acting under the influence of hypnosis. Plus, as we outlined on Saturday, there’s a wealth of evidence — from eyewitness testimony to ballistic impossibilities — that contradicts the official version of Bobby Kennedy’s assassination.

Even 50 years on, there are compelling grounds for a thorough re-investigation. Los Angeles law enforcement, however, has vehemently refused to re-open the case.

Now aged 74, Sirhan remains in jail. Since he doesn’t remember shooting Kennedy, successive parole hearings have concluded that he can’t have sufficient remorse to justify parole.

It’s a classic Catch 22: he could be deemed suitable for release —but only if he admits that he intended to commit a murder he can’t remember carrying out.

Adapted by Corinna Honan from The Assassination Of Robert F. Kennedy by Tim Tate and Brad Johnson, to be published by Thistle on June 6 at £11.99. © Tim Tate and Brad Johnson 2018.