Dr Keightley built up a detailed archive of material he has now turned into a biography of Brady that provides a disturbing and unique insight into the man himself - and the nature of evil.
My first meeting with Moors murderer Ian Brady was chilling. He was tall and sinister, wearing a black polo neck sweater, blue jeans and dark glasses.
As he towered over me, I saw myself reflected in the lenses - and realised that, in their dying moments, this must have been the last view his young victims had of him.
I had come to see him in Ashworth Hospital, a high security psychiatric unit, one Sunday afternoon in 1994, 28 years after his conviction - along with his girlfriend Myra Hindley - for multiple murder.
By then I had been corresponding with him for two years. During that first meeting he demonstrated how easy it was to kill someone. Strangulation was best, he told me: simple, silent and quick. He claimed he could do this with one hand.
I asked the question that continues to puzzle and appal us all, even now, more than half a century after his evil deeds, he is dead.
"Why children?" I demanded to know. He answered immediately, not batting an eyelid: "Existential exercises."
Brady was an evil, sadistic psychopath who considered himself an existentialist, in that he believed it was entirely up to him as an individual to live in whatever manner he chose.
He was also a nihilist who thought that life was meaningless, the universe had no purpose, and religion was a delusion.
Five young people died in horrible circumstances in and around Manchester between July 1963 and October 1965, their parents were put through unspeakable anguish, and all, it seemed, because of this man's perverted philosophical view of the world.
I was to explore his reasons further as I got to know Brady in visits over the following years. I quickly realised that he was intellectually gifted and very widely read.
He was clearly one of the most articulate of killers - and all the more fascinating and dreadful for it.
At Ashworth, he spent his daily life alone in his room, refusing to talk to staff or inmates, whom he considered beneath him.
When I came, he let fly, and I was blasted non-stop as he expounded his nihilistic view that this is a world without meaning or morality - a world in which men like him can do as they please.
Our conversations roamed over religion, philosophy and literature. We talked in depth about Dostoevsky, Sartre and Shakespeare. Through all this, I came to follow his perverted thinking and his strange logic.
As he spoke and his grey eyes penetrated the fog from the French cigarettes he constantly smoked, there was something incandescently evil about him. But I never for one moment thought I was speaking with a madman. He didn't feel he was insane either.
"The morons out there are the ones who are mad," he told me contemptuously. "People who live conventional, dull, boring lives."
If there was a single word that summed him up, it would be contempt - "my contempt for everyone who breathed," as he once put it: contempt for religion, authority, respectability, convention. Contempt even for himself.
One of the first stories he told me about himself was of going to the cinema as a youth in the Fifties and pushing his way out during the final credits of the film to avoid having to stand for the national anthem (which was the tradition back then).
"A man in the aisle stood in my way as the anthem began. In a rage, I lifted him from the ground and threw him between the seats amongst the litter. I stared at him, waiting for any justifiable excuse to murder him."
On this occasion, Brady passed on the opportunity to kill. Soon, though, he would not need an excuse. He would kill simply because he wanted to and he could.
I was first in touch with Ian Brady in 1992, when I was head of religious studies at a sixth-form college in the West Midlands. The mother of Lesley Ann Downey - one of the victims - came to speak to my students about her inability to forgive.
It was she who suggested that I contact her daughter's murderer. I wrote to him, and eventually the man whose name was enough to induce total revulsion in people, agreed to meet me.
I came to be a regular visitor of his; almost the only one apart from the late Lord Longford.
I made monthly, five-hour visits and we talked on the phone every day.
He also wrote fortnightly letters to me - often marked "DESTROY" in red block capitals, a demand I only sometimes complied with.
He opened up to me in a way he never would to policemen, psychologists or journalists.
Unlike Hindley, who sought high-profile supporters and was constantly campaigning to be released on parole, he accepted that he would never again be a free man. He would live and die in prison.
He bequeathed all of his property to me. His possessions held in store at Ashworth were delivered to me long ago, including his vast number of books, each one with his scribbled comments in the margins.
Now that he is dead, I will receive his cell property. I probably got to know him better than anyone else still alive, yet I have to recognise that what he told me may not be the absolute truth. But it is the truth as he saw it. This is therefore the first and only account of the Moors story told in detail by Brady himself.
It has never been revealed or published before.
'I'll be a proper criminal'
As a young man, Ian Brady was a delinquent and a petty thief with a very high opinion of himself.
He drank to excess, went round in a gang, got into fights and dreamed of becoming a bank robber. But as a criminal, he was small beer.
Indeed, the offence for which, at the age of 17, he was arrested and jailed - the theft of some lead - he probably did not commit but confessed to in ignorance and error.
The injustice, he told me, proved to be a watershed in his life.
"I vowed vengeance. If they wanted me to be a criminal, then I said to myself that I'd be a proper one."
But what took his criminal activities into a new dimension - becoming one of Britain's most notorious murderers of all time and a symbol of out-and-out evil - was when the peroxide blonde Myra Hindley came into his life. Hindley, who died in prison in 2002, aged 60, always maintained that she had been manipulated by Brady into murder.
This infuriated Brady and he never wavered in his insistence to me that she had been not only a willing partner in all their dreadful deeds but one who, as we shall see, surprised even him with her sheer ruthlessness and enjoyment of killing.
Their meeting, he told me, was like 'the arc of electricity between two electrodes - shades of Frankenstein.
"When we were together, there was a third entity, an intoxicating, unified force, something intangible that possessed a power beyond both of us."
He had, he explained as he told me about her, made good use of his two years in Borstal, a juvenile prison camp, immersing himself in the works of authors such as Camus and Dostoevsky who would later have such an impact on his thinking, sowing the seeds of what would come to be his obsessive belief that life had no meaning.
But he also read up on accountancy - which meant that, after his release, he was able to talk his way into a job as a stock controller at Millward's in Gorton, Manchester, the Lancashire distributor for the massive Imperial Chemical Industries, ICI.
It was a way of appearing respectable while he and two mates were planning and carrying out robberies.
The thieving was so successful that he was able to buy himself some sharp clothes and a motorbike.
Six months after he started there, Hindley arrived to work in the same office. He was indifferent to her at first. He dictated letters, she typed them.
But Hindley fancied Brady from the moment she first saw him. He was tall, good-looking and shy.
There was - as she wrote in a piece for the Guardian in 1995 - "an immediate and fatal attraction, although I had no inkling then of just how fatal it would turn out to be".
It took her a whole year to get him interested. When they finally went on their first date, it was to the cinema, though the film they saw was not Judgment At Nuremberg, about the trial of the Nazis, as has often been claimed, but, surprisingly, King Of Kings, the epic about the life of Christ.
He walked her home and at the end of the street they kissed. His hands were everywhere. She was wearing a girdle. He told her he didn't like them because they accumulated stale sweat. She never wore one again.
The following evening was Christmas Eve and Ian took Myra to see another film, El Cid. He then started to walk her home - but they stopped on the way to go into a church where Midnight Mass was being celebrated, and sat in empty pews at the back.
Brady was curious but soon reassured himself of his contempt for organised religion and - as if to prove it - urinated against the church wall as they left.
They walked to her home in Bannock Street, and he described to me what happened next: "Myra asked me in. There was just her grandmother asleep upstairs.
"I was accepted on the spot by a ginger-haired brown dog, Lassie, who gave us an excited welcome as we stepped into the living room through the front door.
"Myra and I sat by the fire chatting and drinking our way through two bottles of wine. With the heady wine and the flush of a possible romance, we were sexually inventive through the small hours.
"It was nearly eight in the morning when I put my clothes on, feeling invigorated in every sense - as I invariably did after a night of acrobatic fornication."
For her part, 19-year-old Myra had just lost her virginity. She wrote in her diary: "I hope Ian and I love each other all our lives and get married and are happy ever after."
Brady had different feelings. There was no chance of him "walking blindly into the death trap of marriage and respectability. I had other things on my mind". His bank robbery schemes, for example.
But they began spending more and more time together. When I asked him if he and Hindley had been in love, half expecting him to dismiss the idea as romantic tosh, what he said was: "Of course we were in love."
He went on: "It wasn't just another romance. Something beyond that was growing. I hadn't planned it that way, but I was happy to let things evolve."
Increasingly, he found Hindley was someone he could trust and speak frankly with about his innermost thoughts.
The two of them kept their affair secret in the office, even though they were very soon virtually living together. They would spend their evenings talking in a pub, the Wagon And Horses. They avoided the crowded bar and were usually alone in the snug at the back.
I asked Brady if this was where he began "brainwashing" Hindley.
"No," he replied. "Our relationship wasn't master and slave. It was more like teacher and student. I aired my views for open discussion, nothing more. They were on the table to be rejected or accepted.
"But Myra was surprisingly in tune with me from the very beginning. I was never conscious of having to exert myself to coerce her into accepting my belief in relativist morality. Bit by bit we were moving towards an almost telepathic relationship. She was as ruthless as I was."
Any doubts he might have had about her were dispelled when Hindley, who had been raised a Roman Catholic, told him she had given up religion. She woke up one morning "and realised it was all tosh. We are all just grains on the sand - of no significance whatsoever."
Brady was delighted. They were two of a kind. "When you know it has no meaning, life's much more interesting," he told her.
When she began to bemoan the boring life that probably lay ahead for a working-class girl like her, he put her right.
"Life's a game," he told her. "We are limited only by our imagination." It was better to live for a few moments as a tiger than be a sheep for ever.
Brady was becoming increasingly preoccupied with her and what they might do together.
"Black mushrooms were growing and flourishing in my mind in Myra's company, which filled most of the waking hours."
They were drawing ever closer, bound together by their nihilism. "Dark preoccupations were luring me to take the path of pure existentialism, in which the will to dare all, and suffer the consequences, was becoming all-important rather than the acquisition of cash from my evening criminal exploits.
"Was I mad already? If so, it was catching. Myra was a soulmate. We accepted gladly the indifference of the universe. Our motto was to live fast and die young."
They even began to develop a private means of communication, a secret code of words and body gestures. A "Groucho" - raising the eyebrows quickly twice (like Groucho Marx) - meant "follow the direction of my eyes".
When either of them saw a sexually attractive male or female, desirable to either or both of them given that they were bisexual, they said "DC" - for "delicious creature". This private language would later help them to prey on people as a couple.
One night, Brady asked her if she had a special enemy she would like to eliminate, and she nominated her ex-boyfriend, Ronnie Sinclair.
So would she be prepared to connive in killing him? "Include me in!" she replied. Would she want to be there when he was murdered? "Yes!" she said. "But I want to watch him being humiliated before he dies.
"Take out his false teeth and force him to do whatever you want. I'd love to see him treated like a woman. That would be compulsive viewing."
Brady told me that the subtle cruelty of Myra's requests on this occasion surprised him, and that it wasn't to be the last time.
It was then that he introduced her to Saddleworth Moor, up in the Pennines. He had discovered it on his own, skipping off work one sunny morning and letting his motorbike "take me wherever it wished".
He arrived by chance and was thrilled by its desolation - "vast hills and plains, with exposed black and brown earth spots everywhere, under a pallid canopy of brooding silence".
Now he wanted Myra to see it, too.
They drove out on his motorbike and stopped for her to take in its vastness. "Do you think Ronnie would like to spend eternity here?" Brady asked.
Hindley, on the pillion, put her arms around Ian's waist and replied: "We agree on everything these days, Neddie" - her nickname for him, after Neddie Seagoon, a character in radio's Goon Show.
As they rode back to Manchester, Brady was singing out loud: "Hi-ho, hi-ho, it's off to work we go!" Hindley yelled back: "Just call me Snow White!"
Brady would meticulously plan the killing of Ronnie Sinclair, following him many times to work out how and where. "I felt no hatred towards him," he explained.
"He was simply the target in an exercise; a problem to be solved." In fact they would never get round to killing him, and Hindley challenged Brady on this. Was he going soft, she asked.
The dark agenda that had been simmering in Brady's head for years now broke the surface.
"So you want excitement?" he said to her. "You want to make things happen, Kiddo [his name for her]? The mysterious adventure is about to begin!"
Years later, Hindley would claim that the first murder came out of the blue, that Brady talked about committing "the perfect murder" and suddenly there they were doing it. In fact, she was totally involved in the meticulous planning and as enthusiastic as he was, he told me.
They began by scribbling down their thoughts on paper and then devising a detailed plan of the carnage ahead.
On 30 pages of foolscap they drew up a meticulous "master list" of dos and don'ts.
"The first principle," Brady explained to me, "was that there must be no thread connecting our starting point with our destination, and vice versa."
They would systematically erase all finger prints, tyre prints or anything else that might implicate them in the killings.
Their house would be cleaned of anything that might arouse police suspicions, and any potentially incriminating material then placed into a left-luggage office at a railway station.
Above all - and this was Brady's insistence - there should be nothing to connect them to the people they murdered.
This was what had made him wary of killing Sinclair. But a stranger would be okay, and so he told Myra Hindley to "pick up anyone you choose - it's of no consequence to me".
Then "the hunt, the game" began: "the existential exercise of sheer will power."
He was prepared to die, he told her, and if necessary they would kill each other rather than be caught by the police. "If trapped, we use our revolvers [he had two] to fight our way out. If it's obvious we won't make it, we turn them on ourselves.
"No trial. No prison. Oblivion. Perfect. Better to live and die by choice rather than vegetate. We've talked it through often enough, Kiddo. Now we throw the dice for maximum stakes. Are you hungry for it? Are you up for it?"
According to Brady, Hindley replied: "Of course I'm with you! I knew it wasn't all talk. I was just waiting for the word go."
* Ian Brady: The Untold Story of the Moors Murders by Dr Alan Keightley is published as an e-book on May 22. Available for pre-order on Amazon and other e-tailers.
The murderous rampage begins
On Friday, July 12, 1963, Pauline Reade, a 16-year-old trainee baker, wanted to go to a dance at a social club just ten minutes' walk away from her home in the Gorton district of Manchester.
None of her friends could come - their mothers wouldn't let them - and so she went on her own. Pauline's mum waved her off, thinking how nice her daughter looked with her hair done up. Pauline had on a new pair of white stiletto-heeled shoes, with an ankle strap, which she had bought that day.
Sitting in a parked black van on a deserted street nearby, Hindley heard those stilettos clicking down the road in her direction and guessed she had her prize.
As Pauline passed, Myra attracted her attention. They knew each other vaguely by sight, and she told the teenager she had lost a glove on Saddleworth Moor - would she come and help her look for it? She promised the girl some records as a reward for her help.
Pauline was early for the dance and a trip out with Myra would fill in the time. She took the bait and got in. Myra did a three-point turn and headed for the moor.
Meanwhile, Brady was getting ready in his bedroom at home. He put an elasticised band on his right wrist and slipped a knife under it. He put on surgical gloves and covered them with a leather pair. He then kicked his Triumph motorbike into life and rode to Gorton.
He recalled: "No one who saw me ride past them that night could have guessed what I was about to do. It was enfolding before their eyes, but how could they know?
"For me, it was the beginning of an existential exercise beyond good and evil.
"The streets of Manchester were the backdrop for the scene to which my destiny had been taking me all these years."
The plan was that if he saw Myra Hindley's black van still parked at any of several pre-arranged places, then it meant that she had failed to grab a victim.
But there was no van in sight. It was on.
He remembered hesitating for a moment. "Was I about to step through the final doorway to madness? Or had I already entered it long ago? I recoiled at the idea."
Then he laughed away his last-minute doubts. "Richard's himself again"' he cried, his catchphrase linking him in his mind to the evil king Richard III, and swept off to Saddleworth Moor. Who, he wondered, would be waiting with Myra? A boy or a girl? "I was impatient for its fruition."
Out on Saddleworth Moor, he pulled in at the lay-by he had agreed beforehand with Hindley. She was waiting in the van with Pauline next to her, smoking a cigarette. He thought the girl rather beautiful, delicate and unspoiled by too much make-up.
All three of them, Brady told me, now set off onto the moor, ostensibly to look for the glove. He strode in front, with Hindley and the girl behind him.
"Myra and I knew exactly where we were heading. We had rehearsed it. It was a place on the moor where we would be out of sight from the road.
"I dawdled and pretended I was scrutinising the grass closely, to allow the girl and Myra to walk past me. Pauline's eyes were also focused on the ground. Myra furtively glanced back in my direction. I immediately moved forward to grasp the girl's neck in a Japanese stranglehold.
"She collapsed onto the ground and stared up at me. I knelt down and said: 'Don't make a noise and you'll be all right'. She turned to plead with Myra, 'Tell him to stop!'
"I looked at Myra. Her lips formed a smile, but her eyes had other intentions. Her expression was taunting and pitiless.
"She knelt on the grass to unbutton the girl's coat. She then forced her to sit up before easing off her coat, unzipping her dress and unfastening her bra.
"'Myra! Please don't! Please don't!' the girl cried.
"The girl lay still, passively accepting the violation and her humiliation with half-closed eyes."
Brady and Hindley carried out sexual acts on the girl. Then Brady stood up and told Pauline to get dressed. She put on her clothes and reached for a bronze medallion she had been wearing.
Hindley snatched it from her and snapped: "You won't be needing that where you're going!" Brady was furious with Hindley for giving the girl a warning of what was in store for her, and he slapped her face.
Later, he said, Hindley told him she made the remark because she had a feeling that he was going to let the girl go, and was making sure he didn't.
Then, as the girl stood there with a look of terror in her eyes, Hindley dropped another bombshell. She announced to Brady: "She's Pauline Reade." He knew the name. Reade was a former girlfriend of Myra's sister's boyfriend.
It was a tenuous link but one the police could follow. The "no connecting thread" principle had been breached.
He guessed that Myra had used the situation to rid her sister of a rival, but in doing so she had endangered them.
He wondered what other idiotic risks she had taken. Angry with Myra, he strode back to the car to get what he needed for the next stage. "It was almost dark when I returned and I found Myra only after some anxious moments. I could make out some frenetic movements and I thought the girl was making a fight of it.
"Instead, I found Myra astride the girl's head, pressing down on her face. I saw the glint of a steel kitchen knife on the grass. Myra had attempted to stab the girl's chest, but the knife didn't penetrate her and the blade was bent.
"Myra had punched the girl's head and face. Blood was streaming from her nose and had soaked the front of her dress. Her eyes were closed now. She gasped for breath. I instantaneously withdrew the sheath knife from my wrist and cut her throat. She was dead within seconds."
As Hindley scanned the moor with binoculars to make sure no one else was about, Brady dug a hole in the peat and together they buried the body. Back at Brady's home, they tore off the clothes they'd worn and burned them.
The ashes and the blade of the kitchen knife were thrown into the river after the bike and the van had been meticulously cleaned. Then the couple unwound with a bottle of wine.
Brady asked Hindley if she was sure that no one had seen her pick up Pauline. Myra was sure. But the next day she confessed to him that she had broken their "rules" again: she had kept Pauline Reade's medallion and also four coins that had fallen from her coat pocket.
"I didn't mean to," she said.
Brady was furious. "Theft in the course of murder guarantees you a date with the hangman!" he told her.
But they got away with Reade's murder, despite Brady's fears that Hindley had messed up.
Three months went by, everything was quiet and the two of them were sitting in front of a fire at home drinking cherry wine, Brady told me. He remembered Hindley turning to him and saying: "Neddie, when's the next one?"
"Another one?" he replied. "Are you that hungry, Kiddo?"
Myra responded with "Zzzeee!" - the high-pitched sound she always made when she was excited.
They spread out a map of Manchester and Brady recalled thinking to himself: "Somewhere out there slept a stranger whose life we were soon to enter.
"The days of life left for that stranger were few."
Moors Murders shocked the world
More than half a century has gone by since the Moors Murders, yet they hold a fascination that will not go away, despite the passage of time.
They were the flip side of the so-called Swinging Sixties, traumatic events that shattered all sense of safety and decency in society. It is one thing to cause another person to suffer to achieve some other goal, as in violent robbery. It is another matter to cause a person pain for no other reason than to make them suffer. Here was pure malevolence and we struggle still to understand it.
But people often got Brady very wrong as they searched for clues to explain who and what this monster of a man was.
It was often said, for example, that as a slum-kid growing up in Glasgow, he imprisoned cats, crucified frogs, sliced up caterpillars with razor blades and beheaded rabbits - and that later he got a job in a slaughter house, where he acquired his taste for the sight and smell of blood.
All this was untrue. Brady was never cruel to animals. As a lad, he ran home in tears when he saw an injured horse being put down in the street. He wept again when his pet spaniel died.
He never worked in a slaughter house, though he was once a meat delivery boy, which was how that particular myth began. The idea of butchering animals appalled him. "I could never have brought myself to kill sheep or cattle," he once told me.
"But the idea of killing people never bothered me in the least."
This was the real Ian Brady, a much more chilling man than anyone can possibly imagine, driven by complex motives that are not easily understandable.
Another enduring story is that he and Hindley were inspired by Nazi ideology - that Brady was a Hitler fanatic who collected Third Reich memorabilia from childhood and whose terrible deeds were somehow the outcome of his obsession with the Fuhrer.
But this was not true, either. In fact, as he revealed to me, his political views were Left-wing rather than extreme Right.
The misinterpretation came about because at his trial much was made of his tapes and books on Nazi figures. "I also had tapes of Stalin and Churchill," he told me, "but these were of no interest to the prosecution.
"My interest in the Third Reich was based on aesthetic, not political grounds. I admired the will, boldness and the courage with which Hitler put his beliefs into effect." But he did not identify with Hitler. "No one could. He was unique."
Certainly Brady had books on Nazism. I know because I saw them. But they had been sent to him by people who had assumed he was fascinated by the subject. They went largely unread.
The same went for his supposed obsession with the works of the Marquis de Sade. It is part of the accepted Moors Murders story that the 18th-century French aristocrat's explicit writings combining sex and violence had a decisive, catastrophic influence on him and may even have precipitated the murders.
Brady dismissed this as "nonsense". Again, this was an accusation and an explanation that had been offered by the prosecution at his trial, but he rejected it.
Brady thought they might just as easily have blamed Shakespeare's Richard III, which he read at school, and which was a major influence on him. Brady often likened himself to the cruel king of Shakespeare's play. "Richard's himself again," he would say in his sinister way, to describe the onset of his evil state of mind.
Curiously, I could not find this quotation in Shakespeare's text, but among Brady's property was a video of Laurence Olivier's 1955 film. It was here that I found the elusive sentence.
After a moment in which his better nature almost gets the better of him, the king declares: "Conscience avaunt. Richard's himself again." Brady had watched the film as a teenager and this became his catchphrase.
As for De Sade, Brady had read his works, he admitted, but for the philosophy - life was meaningless and the universe without purpose; therefore, nothing matters - rather than the sexual content, which he described as "repetitive and turgid". He said he was "bored rigid" by it.
The fundamental cause and reason for the unspeakable acts he carried out lay in his conviction that life has no meaning.
"Nothing is true, everything is permitted," he would tell me, quoting Nietzsche, famous for his pronouncement that "God is dead". Brady believed the truth about life to be as bleak as it could be. "In the end, all is illusion or delusion. We each do what we believe is best, that's all."
He called himself an existentialist or a "moral relativist" and his only faith was in chaos and absurdity. "Our yearnings for immortality are comical and preposterous. Life, like death, doesn't give a damn about us."
As for religion, he told me, that was "the self-flattering delusion of mankind that some supernatural force is in the least interested in the life of ants on a speck of dust in the universe". Brady was convinced he was a new kind of killer, of which society would see more and more. These killers would be products of the secular atmosphere that pervaded life in the West as the absolute values of good and evil declined.
He aligned himself with the French atheist Albert Camus, and his copy of Camus's book, The Rebel, was heavily highlighted, particularly a passage that concluded: "Wickedness and virtue are just accident or whim."
But the intellectual influence that meant most to Brady was the Russian novelist Dostoyevsky. His book, Crime And Punishment, hangs like a shadow over the Moors Murders.
Brady's own copy of the book was among the property he bequeathed to me. As I leaf through it, the margins are littered with his comments in purple ink - "marvellous psychological insight", "stupendous observation of human nature!" Brady was 18 and serving a sentence in Borstal for theft when he came across Crime And Punishment and identified with Raskolnikov, the book's anti-hero.
Raskolnikov, a supercilious, poverty stricken student, robs and murders a rapacious old moneylender, a worthless parasite of no use to anyone. Afterwards, he realises money was not the real motive for his crimes, but that the crimes themselves were existential tests of personal will. Brady, as we have seen, went on to use the phrase 'existential exercises' to describe his own murders.
I once pointed out to Brady the irony of him taking Dostoyevsky as his intellectual mentor. The Russian wrote Crime And Punishment to make money to pay for the upkeep of his dead brother's children. How strange that a book that saved children's lives in the 19th century contributed to the murder of children in the 20th. Furthermore, Dostoyevsky wrote that the worst conceivable crime was crime against children.
But my comments were ignored. They did not fit Brady's twisted philosophy.