The 1960s were not kind to Glasgow. The “Dear Green Place” was experiencing a steep, economic decline and an upswing in unemployment and welfare dependency, with all the social indicators which accompany economic malaise: infant mortality, poor health, alcoholism and crime.

Crime was a real concern. In 1965 more than 850 young men had been arrested in Glasgow for possession of an offensive weapon, mostly knives and razors, but also swords and hatchets, and every day seemed to bring with it another murder.

Murder. In the 1950s the murder rate had been roughly similar throughout Great Britain but in the 1960s the rates diverged, with Scotland experiencing a much higher rate than her southern neighbours. Glasgow played an unenviable role in all of this and even as late as the mid-1990s, while there were 1.85 homicides in Edinburgh per 100,000 of the city’s population and 2.17 homicides in London per 100,000, the rate in Glasgow was 4.99.

It is the stories of real people which bring statistics like this to life, and on the 23rd of February 1968 the discovery of the body of a young woman would become the opening chapter in a narrative that even now seems to reveal all that we need to know about Glasgow in the 1960s. This murder is universally accepted as the first in a sequence of three attributed to a serial killer known as “Bible John” and his dark legend continues to haunt Glasgow fifty years later.

Patricia (Pat) Docker was a 25-year-old nursing auxiliary employed at Mearnskirk Hospital. She worked nightshifts which started at 10pm and finished the following morning at eight, and her days off were every other Tuesday, Wednesday and Thursday. Pat lived with her parents – Mr and Mrs John Wilson – at 29 Langside Place in Battlefield, on the south of the city.

Five years earlier, Pat had married Alex Docker, and the following year their son – also named Alex – had been born. By 1968 Alex Snr. was a corporal stationed at RAF Digby in Lincolnshire. The marriage was not going well; Pat and Alex had already discussed divorce and so she brought baby Alex back to Glasgow and decided to live with her parents.

Photographs taken of Pat from around this time reveal a pretty young woman of medium height and slim build, with short brown wavy hair and hazel-coloured eyes.

On Thursday, February 22, 1968, she dressed up to go out dancing. Pat was the height of fashion in her yellow mini-woollen dress, over which she wore a grey duffle coat, which had a blue fur collar. The coat served a practical purpose, as the nights that February were bitterly cold. She carried a brown handbag to match her shoes, and on her right hand wore a wrist watch and wedding ring that had belonged to her grandmother.

Pat told her parents that she was going dancing at the Majestic Ballroom in Hope Street in the city centre, but in fact – for some unknown reason – she had gone instead to the Barrowland Ballroom, where it was “over 25s night”. Perhaps the Barrowland’s reputation was by this time so tarnished that Pat hadn’t wanted to worry her parents about where she was going, or perhaps she just changed her mind. Whatever the reason, this simple inaccuracy about where she had gone dancing was to have major consequences for the police investigation that was to follow.

Pat’s body was found on the Friday morning by Maurice Goodman in Carmichael Lane, just a few hundred yards from Langside Place. Mr Goodman lived in Carmichael Place, but he kept his car in a lock-up garage in the lane. As he approached his garage he saw a naked body lying in the doorway. He jumped back in horror, and then rushed home to call the police. A few minutes later Detective Sergeant (DS) Andrew Johnstone and Detective Constable (DC) Norman MacDonald arrived at the scene to begin their investigation.

DC MacDonald recalled: "There had been a heavy frost that night. We arrived about 8.10am and stopped the car at the Overdale Street end of the Lane. The body was lying with the head towards us. Initially I thought it was a man because of the thin build but when I got closer I could see it was female. She was completely naked, and there was no sign of her clothing. She was lying on her back, with the head turned to the right."

Where was Pat’s clothing? Had she taken off her clothes for whoever had walked her home, or had they been taken off after her death? Had these clothes been destroyed, hidden, or taken away as trophies by her killer?

Dr James Imrie, a police pathologist, was also soon in attendance and he noted that rigor mortis had already set in and that Pat had been dead for some hours.

The pathologist was more certain about the cause of death, for he discovered ligature markings around Pat’s neck, which suggested that she had been strangled. There was no sign of a ligature on, or near the body, but Dr Imrie speculated that the injuries could have been created by a belt. There were also face and head injuries but that none of these injuries were serious enough to have killed her.

A portable shelter was placed over Pat’s body, before it was removed for a post-mortem examination.

Her post-mortem confirmed that Pat had been strangled, although there was no clear evidence of sexual assault, and, at the time of her death, she had been menstruating. This fact was initially simply noted, but in due course would come to take on greater significance.

As spring turned to summer and another winter and spring came and went, the police became increasingly frustrated in their attempts to catch Pat’s killer – a frustration that would become all the greater with the subsequent deaths of Jemima McDonald on August 15, 1969, and then Helen Puttock on October 31 of the same year. At the time, all three women were believed to have been murdered by the same man, after their killer had picked them up at the Barrowland; all three women had been menstruating.

The police had high hopes that they would catch the killer, especially after Helen’s murder. There were witnesses who saw the handsome, well-dressed, and bible-quoting young man who had picked up Helen at the Barrowland and Jean Williams, Helen’s sister, had even shared a taxi with the killer on their journey home from the dancing.

Despite these promising leads no one was, or ever has been, charged with these murders, although the 50th anniversary of Pat’s death allows us the opportunity to think again about her killer. After all, it is now almost a criminological truism that it is the first in a series of murders that provides the greatest number of clues.

If an offender profiler had accompanied DS Johnstone and DC MacDonald to the crime scene what might he have concluded about the circumstances in which Pat was murdered and about the type of person responsible?

Visiting Carmichael Lane five decades after her murder I attempted to make sense of the murder.

I walked past 29 Langside Place, and then into Overdale Street in the hope of finding Carmichael Lane. This was no easy matter. Carmichael Lane is no longer officially listed in street maps of Glasgow, although the lane itself can still be located. It is now overgrown with weeds, with rubbish carelessly discarded here and there. Branches from the trees in the back gardens of the houses in Carmichael Place flop over the lane’s unsteady walls, some of which are covered in graffiti. At the top, it is overlooked by houses in Overdale Street, although as I discovered – having knocked on a few doors in Carmichael Place – in 1968 Mr Goodman used a turning space in front of his lock-up, which would have provided some cover for Pat’s killer.

Did her killer know this, or did Pat suggest that she knew a place where they could steal a private moment?

Mr Goodman’s lock-up was near Ledard Road towards the bottom of the lane, and the killer must have run down the lane and crossed Ledard Road towards the River Cart – where some of Pat’s possessions were eventually found. However, it is not possible to see (or hear) the river from the lane, and so the killer already knew that there was somewhere that he could safely discard Pat’s clothing. In other words, her killer had some local knowledge. He did not run up Carmichael Lane towards Overdale Street, from where he had undoubtedly walked into the lane with Pat, and nor did he turn up Ledard Road.

This seems significant for, in all likelihood, Pat’s killer was also returning home, where he would be safe. Where might this be?

If he had continued south he would have come to the suburbs of Cathcart, Giffnock or Castlemilk, or if he had to go further east he would have reached Croftfoot, Rutherglen or Cambuslang. He might have re-crossed the Clyde, and in doing so, come to Bridgeton, Parkhead, or Shettleston. This is a relatively wide geographical area, but it is inescapably an area that Pat’s killer knew well. These were the suburbs where he felt safe, either because he lived there, or had once lived there, or because he had friends or family who lived there and who could offer him a bed for the night.

Had Pat arranged to meet her killer at the Barrowland? Perhaps, rather than simply changing her mind, she hadn’t wanted to say that she was going to the Barrowland, or with whom she was going, because her parents may have disapproved of that venue and/or of that relationship.

Pat’s clothing and her possessions were carefully removed, and were, with the exception of her watch casing and her handbag, never found. In other words, the killer carefully removed and then disposed of them in some fashion, or kept them as trophies. This is likely to reflect that he had an understanding of how the police would conduct their investigation, and how they would have gone about attempting to establish suspects – largely through fingerprints, hair and blood samples, in an age before DNA profiling.

This suggests that Pat’s killer had offended before, or that he had some insight into policing. As we would now say, he “controlled” the crime scene, and so, for example, he left no fingerprints.

There was no attempt to hide Pat’s naked body. By leaving her corpse in this way, as opposed to disposing of it in the nearby River Cart, her killer was implying that he was not ashamed of what he had done. As far as he was concerned, this was what she deserved, and perhaps he even imagined that there would have been a measure of support for his actions. After all, he would have reasoned, Pat was a married woman, with a young child, and yet had gone out dancing at the Barrowland. What did she expect?

The serial killers that I have worked with have a warped, but, nonetheless an acute sense of morality.

Did Pat’s killer want to have sex with her, or was he disgusted that that was what she wanted? No matter which way one answers this question it is clear that Pat’s murder was sexually motivated.

We should also consider the bruising to Pat’s face. Marks to the face are hugely significant in that they deface – literally “spoil the appearance” – and disfigure the individual. Beating her about the face changed Pat’s appearance, and in doing so her killer sought to limit the significance of her body, and undermine how carefully she had dressed up for the evening’s dancing.

Pat was strangled. This is a particularly intimate form of murder, and when someone is strangled from the front the killer is literally looking into their victim’s eyes, and watching them as their life is squeezed away. This adds to their enjoyment and enhances the moments that they can spend with their victim

Finally, there is another significant clue – another message being left to the police by Pat’s killer – to explain his actions. Despite being careful enough to remove all of Pat’s clothes and her possessions from the crime scene, he left behind her soiled sanitary towel. This was not an oversight, but a carefully considered piece of behaviour.

Pat’s killer remains the central character of this deadly drama. When he danced with her he knew that he had certain ambitions and objectives that he wanted to achieve; ambitions and objectives deeply rooted in his personality and background; ambitions which could only be satisfied by seeking out women at the Barrowland, dancing the night with them, walking them home and then killing them.

In all likelihood he fled from the city after committing the murder, perhaps because his work involved travel.

Pat’s killer was cunning and determined and he had more than likely met her in the weeks after she returned to Scotland and started to work at the hospital.

Today a profiler would say that Pat’s killer was an organized offender and a sexual sadist. So who was he?

I have long suspected that Pat was the first victim of the Scottish serial killer Peter Tobin. When I put this to a very senior detective involved in Operation Anagram – which had been set up in the wake of Tobin’s murder of Angelika Kluk in Glasgow in 2006 – he readily agreed. After killing Angelika, and placing her body under the floor, near the confessional of St Patrick’s Church in Anderston, where he worked as a handyman, Tobin fled to London and was subsequently arrested at University College Hospital, where he had been admitted under the name of James Kelly. These behaviours are significant, as Tobin had a long history of using false names, attaching himself to hospitals and churches, and was known to abscond from areas where he was wanted by the police.

In 1968 Tobin was living in Shettleston, although his work would take him out of the city for weeks at a time and we now know enough about his sexual and sadistic interests from his then-partner to see his signature in how Pat was killed, and what was left at the crime scene.

“So, why not go public?” I asked this senior policeman.

His reply reminded me of the power of legends and how they retain a hold on the public’s imagination.

“Och, we don’t want to get caught up in all that Bible John stuff,” he said, winking, as if doing so wasn’t “real” policing.

The detective’s silence is matched by Tobin, who has consistently refused to reply to the letters that I have sent to him asking for an interview.

Sadly, these respective silences will conspire to prolong the legend of Bible John and, of course, they do nothing to bring Pat’s killer to justice.

Professor David Wilson is Emeritus Professor of Criminology at Birmingham City University