NO UNSOLVED case is closed as far as the new assistant chief constable of Wiltshire Police is concerned.

Former murder squad detective Mark Cooper, who led the team that solved some of Dorset’s most horrific homicides, said it was "not in his psyche" to leave investigations unsolved

Mr Cooper, a police officer of 27 years’ experience, told the Adver one of the first things he did after joining Wiltshire Police a month ago was to order a review of cold cases. He added: “No case is finished. We will continue to review and look at all type of crimes that have been reported.”

Pressing the point home, Mr Cooper said: “No case is closed.”

The senior police officer, who is one of two assistant chief constables to join Wiltshire Police this summer, did not specify any specific cases likely to be actively investigated. However, the news could bring comfort to families who have already had to wait decades to see perpetrators brought to justice.

Last night, Wiltshire Police confirmed that one of their most high-profile cold cases remained just that: unsolved. In 2017, officers investigating the disappearance of Swindon sex worker Sally-Ann John appeared on Crimewatch to re-appeal for information more than two decades after the 23-year-old was last seen. A spokeswoman said: “This case remains a live cold case review.”

For Mr Cooper, his opposition to dropping cold cases stems from his own experience as a detective on Dorset Police’s major crimes team.

Sally-Ann John Picture: BBC CRIMEWATCH

He cites as his proudest moment bringing killer Danilo Restivo to justice in an investigation that lasted nine years. The Italian murdered Heather Barnett in Bournemouth in 2002, a staged killing that saw the judge who sentenced Restivo to life imprisonment describe him as a depraved and calculating killer.

The investigation took years of meticulous work, chipping away at details and waiting for forensic techniques to develop.

“I lived the murder of Heather Barnett and owed it to the family to get a result. I was immensely proud to sit in the court after nearly a decade of trying to bring this person to justice,” Mr Cooper said.

“I was very clear about who was responsible and to hear those words from the judge were probably the proudest moments of my career.

“I’ve always had this notion that we leave no stone unturned. Leaving a murder investigation unsolved is not in my psyche.”

Mark Cooper, 47, joined the police in 1991. He was still a probationer constable when he was one of the first on the scene at a murder in Weymouth, where he started his career. He told the Adver: “I was interested in complex investigation and I wanted to be a detective. I very early got exposure to that type of high-level homicide investigation.”

Prior to joining Wiltshire Police he was assistant chief constable at the Dorset force.

PROFILE: Mark Cooper, new assistant chief constable for Wiltshire Police

When Mark Cooper has something to mull over he heads for the beach.

A keen kitesurfer, the Wiltshire assistant chief constable can be found on the waves by the Dorset coast.

But it is a point of principle for the 47-year-old father of three that he is always available to his officers in a crisis, carrying his mobile phone with him in a waterproof pouch as he takes to the sea.

He said: “If somebody needs to speak to me and I’m out in the middle of the ocean I’m quite happy to take the call.”

Speaking to the Adver at Gablecross police station, Mr Cooper wears the black t-shirt and stiff boots of any beat officer.

Mr Cooper Picture: DAVE COX

But the experienced police officer has spent most of his 27 year career in a suit, not a uniform.

He joined Dorset Police in 1991, swiftly moving to a job in Weymouth CID. It was there, he says, he learned the basic skill of his trade: attention to detail.“We use the A.B.C. of policing: assume nothing, believe no one and check everything,” he said. “I was taught very early it’s about being thorough.”

Mr Cooper rose through the ranks and, as an inspector with the major crimes team, investigated the horrific murder of Bournemouth mum Heather Barnett in 2002.

In 2011, he passed with distinction a masters degree in criminology from Cambridge University. His dissertation looked at links between those involved in organised crime in Dorset.

Organised crime remains an interest for the assistant chief constable, who at Wiltshire Police is responsible for teams investigating serious and organised crime.

And he says the county is well placed to tackle the issue of County Lines, organised city-based drug dealers muscling in on Wiltshire’s heroin and crack cocaine trade: “It’s an absolute priority for the organisation.”

In his first newspaper interview since joining Wiltshire Police, Mr Cooper emphasised the importance of partnership working and said he was interested in trying to cut red tape for his officers. The force’s focus was on providing “outstanding service to the public”, he added.