She was a bubbly blonde teenager with her whole life ahead of her. At 16, farmer’s daughter Hannah Pearson was a former school captain who had just emerged from a difficult two-year battle with anorexia. Who knows what she might have gone on to achieve?

Hannah never got the chance to find out, for on a warm July evening last year her life was brutally cut short when she was throttled to death by a young man eight years older.

It is a terrible end, rendered all the more disturbing when you learn the context: Hannah’s killer, James Morton, was obsessed with sexual strangulation, and her death came about after he plied her with alcohol, forcing her to recreate a scene he had watched in a porn film.

Shockingly, the court heard that Morton had previously attempted to throttle a woman partner, though she had escaped with her life.

Hannah Pearson was killed by James Morton, who was obsessed with sexual strangulation, and her death came about after he plied her with alcohol, forcing her to recreate a scene he had watched in a porn film

Hannah was not so lucky. While a panicked Morton called 999 when she stopped breathing, she was pronounced dead shortly after her arrival at hospital.

Morton denied murder, but last month was found guilty of manslaughter after a trial at Nottingham Crown Court in which the links between Hannah’s death and her killer’s enjoyment of violent pornography were made plain.

Sentencing him to 12 years in prison, Judge Mrs Justice Carr told him he subjected Hannah to ‘auto-erotic sexual activity’ when she could not object. ‘You enjoyed the domination, something you had seen on a porn DVD previously, and had also tried with at least one previous girlfriend.’

The distressing case once again raised worrying questions about the relationship between the ready availability of violent pornography and the rape and murder of women and girls.

The easy availability of porn on smartphones and computers — which the internet giants seem so unwilling to crack down on — has made the problem worse.

The feminist activist Andrea Dworkin may feel she has been proved right. She argued that by depicting women as men’s willing sexual playthings, porn contributes to rape.

While there are no formal statistics available from the Home Office or the Ministry of Justice on the links between viewing porn and committing violent sex crime, there have been a number of murders in recent years in which the perpetrators have been known to have viewed — or been regular viewers — of extreme porn.

The victims included Jane Longhurst, whose violent death in 2003 at the hands of porn obsessive Graham Coutts led to a change in the law after Jane’s mother campaigned for a ban on internet sites which promoted violence against women for sexual gratification.

April Jones, five, was abducted in Machynlleth, in Wales, in the autumn of 2012 — being last sighted getting into a van that belonged to Mark Bridger, a former abattoir worker

The Labour government did not go quite that far, but in 2009 it did introduce new laws making it a criminal offence to possess pornographic images that depict acts which threaten a person’s life.

Yet according to Professor Clare McGlynn, a law professor at Durham University and an expert in the legal regulation of pornography, little can be done to prevent access to such material which she believes creates ‘cultural harm’.

‘Our attitudes and behaviour are shaped, though not exclusively, by our social environment. Where pornography is part of that environment, it is reasonable to expect it to be one contributing factor to these attitudes.’

Here are some of the disturbing cases in which women have lost their lives at the hands of men obsessed with violent porn — often specific types of pornography which they then copy in the most chilling fashion.

THE BRILLIANT MUSICIAN

Jane Longhurst, 31

A talented special needs teacher and musician, her partly decomposed body was found burning in woodland in West Sussex in April 2003. The police trail led to Graham Coutts, 39, from Reading, who was the boyfriend of Jane’s best friend, Lisa. Jane, also from Reading, was a regular visitor to the home the couple shared.

It transpired that Coutts strangled Jane with a pair of tights before keeping her body in a storage unit for a sexual thrill.

His murder trial laid bare the extent of his fascination with strangulation. It started when he was a teenager and he progressed to looking at violent pornography on the internet, particularly footage of simulated strangulation, rape and necrophilia.

Graham Coutts, 39, strangled Jane Longhurst with a pair of tights before keeping her body in a storage unit for a sexual thrill. He downloaded a ‘horrific’ collection of strangulation images the day before Jane’s death, spending two hours on the internet looking at sites dedicated to necrophilia

He downloaded a ‘horrific’ collection of strangulation images the day before Jane’s death, spending two hours on the internet looking at sites dedicated to necrophilia. He also visited these sites after the murder, and sometimes just minutes after visiting Jane’s body at the storage unit where he had deposited her lifeless body.

In court, Coutts insisted Jane’s death was an accident, testifying that he had wrapped the tights around her neck as part of a consensual sexual practice known as erotic asphyxia. Coutts is now serving a life prison sentence.

THE LANDSCAPE ARCHITECT

Joanna Yeates, 25

The landscape architect was a warm-hearted young woman who lived in a garden flat in Bristol with her boyfriend.

Next door was a perverted fantasist named Vincent Tabak. The Dutchman’s infatuation with Joanna and his obsession with internet images showing chilling depictions of women being choked proved to be a fatal combination. Joanna’s partially clothed, frozen body was found at a roadside in Somerset on Christmas Day in 2010, eight days after she had been reported missing.

A post-mortem showed she had been strangled in a frenzied attack in which she also sustained more than 43 separate injuries.

Joanne Yeates was murdered by perverted fantasist Vincent Tabak, whose infatuation with Joanna and obsession with internet images showing chilling depictions of women being choked proved to be a fatal combination

Police stand guard outside the flat of Joanna Yeates in Bristol, where she lived with her boyfriend

Tabak was charged with Joanna’s murder. He denied guilt — claiming her death was an accident. It happened, he said, after he misinterpreted an invitation by her to share a drink and then tried to silence her when she screamed after he tried to kiss her. Joanna’s terrible injuries — she had fought for her life — suggested otherwise.

It became clear that in the months leading up to the killing, Tabak had viewed violent internet pornography that depicted women being bound and gagged, held by the neck and choked. His computer also contained stored images of a woman exposing her breasts who bore a striking similarity to Joanna.

Clearly, Tabak had graduated from ‘observer to perpetrator’.

His fascination with illegal explicit images, meanwhile, did not end with those of strangulation. Police discovered that Tabak, now in jail for life, had child porn on his laptop.

THE PETITE TEENAGER

Becky Watts, 16

The teenager died in February 2015 after being suffocated in her own bedroom in Bristol and stabbed in the abdomen 15 times — with her body being dismembered with a circular saw, packed in plastic and preservatives and hidden in a garden shed. Her killers were her step-brother, Nathan Matthews, and his girlfriend, Shauna Hoare.

Police found 236 sadistic images and 21 movies on Matthews’s laptop, among them a film entitled ‘Virgin teen gets raped in own house’ which he is believed to have watched before killing Becky.

Becky Watts was murdered by Nathan Matthews. Police found 236 sadistic images and 21 movies on Matthews’s laptop, among them a film entitled ‘Virgin teen gets raped in own house’

The teenager died in February 2015 after being suffocated in her own bedroom in Bristol and stabbed in the abdomen 15 times. Pictured, police searching for the teenager's body

Killer: Nathan Matthews' girlfriend, Shauna Hoare

Indeed, she had been scared of him for years, something she had confided to a child psychologist to whom she had been referred for problems with anxiety.

She also told her best friend who said Becky had confided in her how Matthews had taunted her with threats to kill, graphically describing the wounds he would inflict on her.

At Matthews’s trial, jurors were told of his sexual interest in petite teenage girls and ‘threesomes’.

He possessed a cache of online porn showing teenagers, some dressed as schoolgirls.

In one piece of footage stored on a phone kept at his home was a video showing the rape of a teenager in which the attacker put his hand over the victim’s mouth.

Matthews had been downloading such videos for the previous six years. Asked in court how often he watched porn, he replied that ‘on average’ it was ‘every other day.’

THE A-LEVEL STUDENT

Georgia Williams, 17

Georgia, a popular former head girl, was invited by family friend Jamie Reynolds to participate in an ‘artistic’ photoshoot at his parents’ home in Wellington, Shropshire, 2013.

What she didn’t know was that he harboured a secret fascination for hanging, strangulation and necrophilia. These sickening obsessions led him to amass 16,800 images and 72 videos of sexual violence on his computer, including images of women he knew with ropes digitally added around their necks. Reynolds chose Georgia as his victim so as to fulfil a long-standing desire to hang a girl and sexually assault her.

His planning was meticulous — he spent five months composing a ‘storyline’ describing Georgia’s murder on his phone before carrying out the killing just as he had planned.

Georgia Williams died at the hands of Jamie Reynolds, who harboured a secret fascination for hanging, strangulation and necrophilia. These sickening obsessions led him to amass 16,800 images and 72 videos of sexual violence on his computer, including images of women he knew with ropes digitally added around their necks

Reynolds, 23, lured Georgia to her death after asking her to pose for him with a rope around her neck. In a photo found by police, she is captured smiling at the camera with the noose around her neck on the landing of the house. Just afterwards, Reynolds kicked away the box she was standing on.

Reynolds, who was obsessed with redheads like Georgia, and snuff movies in which women are killed on screen, also took horrific photographs of her naked body and took her jewellery to keep as ‘trophies’.

Only after being sentenced to a whole life tariff for her murder did it emerge that Reynolds had tried to strangle another teenage girl five years earlier in an assault.

In that attack, he used the same photoshoot ruse to lure the 16-year-old to a place where he then attempted to strangle her. Thankfully, the girl fought him off and reported the attack to the police. He was caught and — remarkably, given the seriousness of the offence — given a warning.

The let-off was particularly distressing considering that during a failed appeal over the case involving the murder of Georgia, the Lord Chief Justice, Lord Thomas said he had ‘no doubt’ that violent internet porn had ‘a dramatic effect’ on crimes.

‘I cannot believe someone would have thought through how to do something without having read it,’ he said.

‘What is available to download and see is simply horrific and it played a real part in the way this murder was carried out.’

THE PRIMARY SCHOOLGIRL

April Jones, 5

The young girl was abducted in Machynlleth, in Wales, in the autumn of 2012 — being last sighted getting into a van that belonged to Mark Bridger, a former abattoir worker.

He had long harboured sadistic sexual fantasies about young girls — and according to police had spent months if not years building up to playing out in real life the pictures he had seen on film.

Officers found he had adult images of hard-core porn and a library of graphic images, some depicting very young girls suffering sadistic abuse by adults.

April Jones was last seen getting into a van that belonged to Mark Bridger, a former abattoir worker. He had long harboured sadistic sexual fantasies about young girls — and according to police had spent months if not years building up to playing out in real life the pictures he had seen on film

Police at the home of Mark Bridger in Ceinws, Mid Wales

Detective Superintendent Andy John said: ‘The unhealthy interest he has in indecent images of children is a clear indicator that this individual was going to commit something as horrific as he did.’

On the day April was abducted, Bridger had looked at an image from his collection of pictures showing a young girl bound with gaffer tape being forced to have sex with an adult. When his van was recovered, there was a roll of gaffer tape on his dashboard.

In court, Bridger claimed he had accidentally run April over in his car and in his panic could not remember disposing of her body. He was found guilty and given a whole life sentence.

April’s body has never been recovered, although police believe Bridger scattered her remains across the countryside near her house.