POLICE revealed last night they were calling in a world-class team of forensic experts in a bid to catch the killer of Ann Heron.

Mrs Heron's bikini-clad body was found in a pool of blood outside the home she shared with her husband, Peter, on the outskirts of Middleton St George, near Darlington, on August 3, 1990.

The 44-year-old's throat had been cut while she sunbathed.

Durham Police said some of Britain's foremost forensic scientists would carry out new tests on potentially crucial evidence recovered from the crime scene, having previously worked on the successful investigation into the murder of British backpacker Peter Falconio, in Australia.

The team, who also helped Spanish police investigating the Madrid bombings, are believed to be the only scientists in the world able to analyse samples that are so small they cannot be seen.

Last night, the detective leading the investigation, Chief Superintendent Dave Jones, said: "This latest twist in the case yet again underlines our determination to do everything we possibly can in our unrelenting quest to identify the person who killed Mrs Heron."

He went on to reject claims about the timing of the police announcement.

Police have previously hailed a number of breakthroughs in the long-running murder hunt, but a successful conclusion to the inquiry has so far eluded detectives.

In November 2005, they arrested Mrs Heron's husband, Peter, at his home in Lanarkshire, Scotland, and charged him with murder following a cold case review of the inquiry that used the latest forensic techniques.

But the case against the retired businessman, who denied any involvement in his wife's death, was discontinued after a review of the evidence.

Mr Heron subsequently lodged a claim for compensation against the Durham force for wrongful arrest, malicious prosecution and false imprisonment.

The Northern Echo has learned that this has never formally been pursued by Mr Heron's legal team and has effectively been dropped.

However, there has been recent correspondence between Mr Heron's solicitor, Peter Wishlade, and the Crown Prosecution Service (CPS) - which supported the murder charge - which is understood to be critical of its handling of the affair.

Chief Supt Jones said the announcement of the involvement of specialists from the Forensic Science Service, based in Wetherby, West Yorkshire, had "nothing whatsoever to do with any exchange of letters or correspondence between Mr Wishlade and the CPS".

He said of the development: "We have just completed a further review of what we regard as the crucial samples from the scene of Mrs Heron's murder and the chief constable has agreed to commission national specialists from the Forensic Science Service, who are at the very forefront of this work, to apply the latest laboratory techniques to those samples, some of which are being examined for the very first time."

The results of the latest battery of examinations were not expected to be known until the early summer, he said.

Mr Wishlade confirmed he had written a recent letter to the CPS about its involvement and suggested this was the motivation for the police announcement.

He said: "We are taking this matter the case brought against Mr Heron further with the CPS and I have written to them asking certain questions.

"There is nothing at all fresh that I know about in this information from the police.

"As far as I am aware the last forensic report provided also used the latest forensic techniques and proved absolutely nothing.

"My client's position continues to remain exactly the same."

Durham police's actions have been backed by a former police chief who now acts as a forensic science consultant to UK forces.

Geoff Knupfer, a former detective chief superintendent with Greater Manchester Police, said: "The police remit is to investigate homicide at its most serious and it would be wholly appropriate in my view for a senior investigator to apply new techniques as and when they become available to all outstanding unsolved cases."

Mr Knupfer said that although he had no detailed knowledge of the Heron case, the chances were that, as well as blood samples, anything from hair to finger impressions and sweat were being examined.