Cooper murdered millionaire farmer Richard Thomas, 58, and his sister Helen, 54, at their burnt-out Pembrokeshire mansion in December 1985.
He murdered tourists Peter Dixon, 51, and wife Gwenda, 52, on the final day of their holiday four years later. The couple, from Oxfordshire, were attacked as they walked along a coastal path near Little Haven, Pembrokeshire, in June 1989.
Both couples died after being blasted at close range with a shotgun.
At one point there was speculation the Dixons died because they stumbled on a cache of IRA weapons.
Cooper, aged 66, denies shooting to death Oxfordshire holidaymakers Peter and Gwenda Dixon as they walked the Pembrokeshire Coastal Path in June, 1989.
He also denies murdering brother and sister Richard and Helen Thomas at their home, Scoveston Park, in 1985. They had also been shot with a 12 bore shotgun.
Despite Cooper’s denial of his crimes, a jury unanimously found him guilty of the four merciless killings, which go back more than 25 years.
He was also found guilty of raping a teenage schoolgirl, sexually assaulting another, and five separate attempted robberies, all in March 1996.
Judge John Griffith Williams passed directly to sentencing Cooper after the verdict.
He gave him four life sentences for the killings, telling him: “The murders were of such evil wickedness that the mandatory sentence of life will mean just that.”
Cooper was unable to listen to the judge’s remarks without shouting words of defiance.
As the judge outlined the terrible details of one of the murders, Cooper shouted: “This is utter rubbish and what you have kept from this jury is going on the internet.”
Later on, Cooper interrupted with: “Evidence has been kept from the jury and I do not blame them.”
Moments after the verdict was announced, members of Cooper’s family stormed out of court, shouting: “We will be there for you, John.”
Judge Williams told Cooper: “I am confident that you will never express any remorse and so help the victims come to terms with their loss.
“You are a dangerous man who is a highly organised predatory burglar whose hallmarks were balaclava, gloves and shotgun.
“Each of your offences were well planned and so it was that you evaded arrest for so long.
“Indeed, but for the advances of forensic science, you may well have never been brought to justice.”
Half a lifetime ago Cooper was liberated from the daily need to work by a windfall spot-the-ball win of £90,000. The 66-year-old pensioner was 33 in 1978 when fortune smiled and transformed his life.
The cash sum by today’s standards would be equivalent to winning close to £1 million. In addition to the cash, Cooper was presented with a brand new Austin Princess car, itself worth £4,000.
At the time he was working as a welder’s mate and his wife was the manageress of a local fish and chip shop. With two steady incomes, the couple appeared to have no financial worries and Cooper certainly no need to steal.
It has never been suggested that he, at that point, had already embarked on a life of crime, although it is likely. His psychological make-up, showing clear psychopathic character traits, meant he was well suited to such a life.
But within seven years of the win he was to murder Richard Thomas, 58, and his sister Helen, 54, at their home. The brutal double killing appears to have been a failed burglary attempt, assumed to have been carried out by a man desperate for money.
It indicates that by then Cooper was already in need of cash and had turned to crime to make ends meet. His windfall, cautiously invested, could have made him and his family economically secure for life.
In little more than a decade he was a quadruple killer and burglar whose actions heaped misery on scores of innocent victims.
The money he won appears to have largely been dissipated on over-ambitious attempts to set himself up as a farmer. He bought at least two farms, in the Milford Haven area, on separate occasions but failed to make a success of things. Each was eventually sold for less than he had paid for them, although he claimed in court the loss was not great.
A golden opportunity to transform his life appears to have been squandered, along with a great deal of cash.
Television never taught him the potential forensic pitfalls to look out for and avoid during a life of crime. He retained an array of items, from weapons to his own clothing and that of his victims, which subsequently linked him to the murders.
The pains he did take, such as wearing gloves which limited the chances of leaving DNA behind, did offer partial protection.
It is ironic, therefore, that the first major forensic breakthrough linking Cooper to the murders would come from a discarded glove.
It came while Cooper was behind bars serving his sentence for burglary. A forensic review of all the case evidence from 2005 saw LGC Forensics, the UK’s largest privately-owned forensic science service, brought in. Energetic efforts to uncover all and any links between Cooper and the killings took in all items retained from the earlier burglary trial.
Among them was a single used glove referred to in the trial as reference number BB109.
“That number will stay in my mind for the rest of my life,” said Roger Robson, a fibres expert brought in by LGC Forensics as a case consultant. “When we found fibres from that glove on the branches used to hide Gwenda Dixon’s body, that started the whole ball rolling.”
He also betrayed a certain respect for Cooper’s unsophisticated efforts to hide what he had done. “I think you have to give him some credit,” Dr Robson said. “He was very savvy in some ways because he wore gloves in all of the crimes of which he was convicted, which reduces the potential for leaving DNA.
“He also made a reasonable attempt to cover his tracks. But all humans make mistakes and the fact that criminals make mistakes is just an aspect of a case.”
Alarmed police closely tracked the movements of Cooper during months of secret surveillance after his release from prison. Cold case detectives were still hunting for a “golden nugget” of forensic evidence when the multiple murderer was released after a decade behind bars for burglary at the end of 2008.
While urgent efforts to find breakthrough evidence continued, police were forced to keep tabs on the man they were convinced was guilty.
Cooper was not arrested for two double shotgun killings, a rape and a host of lesser offences until May 2009. By then he had been under intense police scrutiny for months to ensure he posed no danger to public safety.
Dyfed Powys Police were understandably fearful when the man they knew to be a multiple killer was released on licence.
“Clearly, I felt at that stage he was a very, very dangerous individual,” said Detective Chief Superintendent Steve Wilkins. “Obviously it was a worry, but I had total confidence in the local police to monitor any risk he may have represented. Significant resources were assigned to it.”
He added: “At the time he was due for release we were in contact with the Probation Service and also the Mappa (Multi-Agency Public Protection Arrangements) agency but had no influence in relation to how long he had left in prison.”
Despite an accumulation of forensic evidence, police knew from previous experience that Cooper would never come clean. He had to be comprehensively caught with every angle covered and every question answered.
“Even faced with the most damning evidence, he was not an individual who would admit anything,” Mr Wilkins said.
“We needed that golden nugget of evidence.”
As it happens, forensic scientists working in early 2009 discovered two. One was a pair of draw-string shorts found in the bedroom of Cooper’s Jordonston small-holding home in 1998.
Seized during the police search in connection with the burglary trial, it was 11 years before they were to deliver up their secrets.
Cooper claimed the shorts were his but they originally belonged to Gwenda Dixon and were taken from the murder scene 20 years before.
Used by Cooper for years afterwards, tests were to confirm they had a blood mark with a DNA profile of murder victim Peter Dixon. A flake of Mr Dixon’s blood was also found adhering to the shorts, the hem of which had been altered.
Inside the hem a trace of human fluid was found which proved to have the DNA profile of Julie Dixon, the daughter of the murdered couple.
The second nugget was another partial DNA profile of Mr Dixon from paint flakes taken from the hand-painted barrel of a sawn-off shotgun. The gun, used by Cooper in the Sardis robbery for which he was convicted, was found hidden in a hedgerow close to his home in 1996.
When the black paint was stripped away a microscopic bead of blood was found giving Mr Dixon’s full DNA profile.
Taken together police felt confident they had indisputable evidence proving Cooper was a murderer.
Traits of a psychopath
Quadruple killer John Cooper ‘demonstrated all the classic character traits of a psychopath’, experts say.
The personality disorder is characterised by an abnormal lack of feeling towards others, masked by an ability to appear outwardly normal. Psychopaths lack a sense of guilt or remorse for any harm they cause others, according to experts. They blame what they have done on someone else and tend to deny outright any wrongdoing.
Cooper was caught and jailed in 1998 for being a prolific burglar who preyed on his unsuspecting neighbours for years.
Despite being unanimously convicted of burglary by a jury, even today he continues to insist on his innocence.
In addition to being a one-man crime wave in and around Milford Haven where he lived, Cooper was also a multiple murderer.
In line with the character traits of the psychopath, he possessed the ability to live untouched by the brutality of his secret life. While a normal person might be oppressed by the terrible knowledge of murder, Cooper suffered no such qualms.
Despite carrying out such chilling crimes, he had the ability to return home and switch back to normal life. His lack of empathy for others also allowed him to kill for little or no provocation, and for almost no financial gain. In the cases of the Thomases and the Dixons, his financial reward for murder was descried as “negligible” during the trial.
In the case of the 1996 attacks and rape on a group of five teenagers, Cooper was thought to have let them live only because there were so many. Detective Chief Superintendent Steve Wilkins, of Dyfed Powys Police, headed the force cold case investigation from 2005 onwards.
“I do believe that he can be described as an individual with psychotic tendencies,” he said. “It is clear that he was an individual who could resort to significant and desperate violence and the killing of people. In my view, that was primarily and simply a means to an end.”
He added: “The next day he would go back to his darts, his family life, such as it was, and no doubt he was a caring grandfather to his granddaughter.”
In court Cooper portrayed himself as a popular local figure regarded in the community as a bit of a “character” – known to almost everyone.
The reality, according to the police, was quite different.
“John Cooper did give a view of himself as a popular man,” Mr Wilkins said. “What we found from our inquiries was that very few people knew him or were close to him and people who did know him gave him a wide berth.
“He was regarded as a character that people did not want to get too close to. “It was the same while he was in prison. He got down and did his time. But nobody got close to him.”
Part of the problem when dealing with psychopathic killers is their general ability to appear normal. They can have a superficial charm about them backed up by a willingness to say anything to anybody without concern for the truth.
Gerard Elias QC, the trial prosecutor, called Cooper “a plausible liar” during his cross-examination, a man willing to say anything to avoid the truth. In his opening, Mr Elias described Cooper to the jury as “a man who is devious and scheming and will stop at nothing, regardless of the consequences for others, to seek to evade justice”.
Another aspect of a psychopath’s mind-set is a distorted sense of the potential consequences of their actions, to others and themselves. They often do not recognise the risk they run of being caught, injured or disbelieved as a result of their actions.
Some experts believe there is neither cure nor treatment for psychopathy. Medication to instil empathy does not exist. They believe, although it is disputed by others, that even talk therapy only teaches psychopaths to better manipulate others.
A general guide used by experts to help diagnose psychopathy can be boiled down to eight specific character traits. While not claimed to be an infallible guide, anyone possessing all eight traits would certainly be a seriously troubled character.
The eight pointers are:
- Glibness/superficial charm;
- Grandiose sense of self-worth;
- Pathological lying;
- Lack of remorse or guilt;
- Emotionally shallow;
- Callous/lack of empathy;
- Failure to accept responsibility for own actions.