Pembrokeshire Murders

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Forensic Casebook

Offence: Murder
Victim: Richard and Helen Thomas, Peter and Gwenda Dixon
Suspect(s): John Cooper

The Pembrokeshire Coastal Path Murders

Between the ages of seventeen and twenty-one, John Cooper had been charged with carrying an offensive weapon, taking a motor vehicle without consent, assaulting a police officer, being drunk and disorderly, and ABH .Then he got married, had children, and seemed to settle down.

Cooper must have been in his thirties in 1978, when he won £90,000 in a Spot the Ball competition. Although it was a huge amount of money at the time, it apparently wasn’t long before it had all been spent and gambled away. In 1983 he embarked on series of burglaries and by the time Cooper went to prison in 1998 he had committed thirty burglaries and a violent armed robbery.

Eight years into his prison sentence Angela Gallop (Group CEO at Forensic Access) was asked by Detective Chief Superintendent Steve Wilkins to assist with Operation Ottawa. Angela and her team were tasked with reviewing two cold-case double murders and a multiple sex assault at gunpoint that had taken place in Milford Haven.


Case One: Murder of Richard and Helen Thomas

The first murder involved the deaths of brother and sister Richard and Helen Thomas. Helen’s badly burned body was found on the ground floor among debris that had fallen with it from the bedroom above as a result of the fire. Richard’s was discovered on a half-landing on the first floor.

Because they both had gunshot wounds, it was thought at first that they’d died as a result of suicide/murder. Then a mud-stained blanket near Richard’s body and a pool of blood with three cartridge pellets in an outhouse raised the possibility that he had been shot in or near the outhouse, then wrapped in the blanket and dragged back to the main house through the dirt.


Case Two: Murder of Peter and Gwenda Dixon

Four years later, husband and wife Peter and Gwenda Dixon were murdered just a few miles away on the Pembrokeshire Coastal Path. They disappeared while on a camping holiday in Little Haven and were reported missing to the police.

Almost a week after they’d last been seen, their bodies were found, partially concealed by broken branches and vegetation, in undergrowth on a flat strip of land at the edge of a precipitous cliff next to the coastal path.

Gwenda had been shot twice at close range. The disturbance to her clothing immediately suggested that she had also been sexually assaulted. Peter had also been shot and his fully-clothed body was discovered nearby, very close to the edge of the cliff.


Case Three: Assault and Rape at Gunpoint Multiple Victims

The third unsolved case involved an attack seven years later on five young people in Milford Haven. The teenagers were walking through a field when they were approached by a man who demanded money, then held them at gunpoint while he sexually assaulted one of the girls and raped another.


Cold Case Review and Forensic Re-examination 

After reviewing the three cases, Steve Wilkins was convinced John Cooper was a prime suspect. And it was because Cooper would soon be eligible for release from prison that Steve asked Angela Gallop and her team for help.

We began by looking for ‘foreign DNA’  (i.e. DNA which was different to that of the victims and could have come from the offender) in all the obvious places: the rope that had been used to tie Peter Dixon’s hands behind his back; his belt; items of Gwenda’s clothing that had been pulled down or pushed up; and swabs that had been taken from their bodies.

The initial DNA work proved inconclusive, so we widened our forensic investigation, starting specifically with textile fibres. We also looked to the crime scene to help us prioritise our search. And almost immediately we started to find blue acrylic fibres on the branches used to hide the bodies and on Peter Dixon’s belt.

As we knew the offender must have handled those branches extensively, it looked as though he had been wearing gloves, which might be another reason why we’d been having so much trouble finding any ‘foreign DNA’ which could have come from him.

Part of Cooper’s burglary MO had been to discard items he didn’t want (including offending gear) in hedgerows as he walked home. Among the discarded items discovered were a large number of gloves, several of which had been knitted from blue acrylic fibres. One of the gloves was made of fibres that matched some of the fibres on the branches and on Peter’s belt, and other fibres were so similar we thought they were probably from its missing pair. It was the breakthrough we’d been waiting for.

Fibre evidence began mounting up and while examining the adhesive tapings (used to collect fibre evidence) from a pair of shorts found in Coopers house we found a tiny flake of blood. DNA testing matched this blood to Peter Dixon.

Further incriminating evidence came from a sawn-off shotgun linked to Cooper which had been found in a hedgerow during the burglary investigations. Forensic examination revealed blood on this with a DNA match to Peter Dixon.  

There were also strong textile-fibre links with the two girls who had been sexually assaulted in Milford Haven. These included fibres found on the inside of the girls’ clothing that could have come from a pair of gloves discovered in a hedgerow, and other fibres transferred in the reverse direction, from the clothing to the gloves.

While evidence built-up there was still a potential question mark over the origin of one bloodstain recovered from inside the hem of the shorts.  DNA testing showed that this blood stain could have come from Peter Dixon’s daughter.  But how was her blood on shorts recovered from Cooper?  Then it dawned on the team - What if the shorts had belonged to one of the Dixons, and when Cooper found them while he was searching through their rucksacks he had decided to swap them for his own blood-stained shorts?

Leading DNA scientist Phil Avenell, also of Forensic Access, was tasked with unpicking this and other complex issues.  Piecing these together, along with close working with the police and lawyers, it was soon established that, far from undermining the critical evidence, what had been found actually supported it.


Guilty: The Verdict and Sentencing of John Cooper

Cooper was tried in 2011 and found guilty of murdering Richard and Helen Thomas and Peter and Gwenda Dixon, and of a serious sexual assault and five attempted robberies of the young people who had the misfortune to encounter him in the field, he was sentenced to life in prison.

Combined with DNA evidence revealed by meticulous searching, this contributed to Cooper’s conviction in 2011. The scientists involved all received formal commendations for their work.

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