DETECTIVES are on the verge of making a significant move in the investigation into one of Britain's most notorious unsolved murders, The Northern Echo can reveal.

Ann Heron was killed as she sunbathed in the grounds of her home, on the edge of Darlington, more than 14 years ago.

The 44-year-old was discovered lying in a pool of blood at Aeolian House, in Morton Palms, by her husband, Peter, on August 3, 1990. Her throat had been cut.

Mrs Heron's murder sparked one of the largest investigations ever undertaken by Durham Police and senior officers remained adamant over the years that her killer would be brought to justice.

Now, detectives are understood to be following up promising new lines of inquiry.

They will hold talks with the Crown Prosecution Service early in the new year, with a view to progressing the investigation, after further discussions with forensic experts.

The news comes seven months after retired detective Ian Phillips was brought in to lead a cold case review of the murder - the first time in Durham Police's history that such a step had been taken.

He has sifted through masses of evidence, including 1,500 forensic samples and thousands of statements, in an effort to uncover the killer.

Detective Superintendent Dave Jones, who is leading the inquiry, told The Northern Echo that the case had developed.

"I fully expect that the whole painstaking examination of the mountain of files and associated paperwork will be completed in the near future," he said.

"During the review, Ian Phillips and myself visited the Home Office laboratories at Wetherby and talked to forensic scientists involved in the original investigation.

"We are developing lines of inquiry with them.

"Very early in the new year, I intend to present a report to the chief constable and also prepare a file that will form the basis for discussion with the Crown Prosecution Service. Those talks will determine the future course of the investigation."

Police have long insisted that the DNA technology would one day exist for the hundreds of tiny forensic samples being held to point to the murderer.

Mrs Heron was attacked, possibly with a scalpel or a handicraft knife, as she lay in her garden.

She had not been sexually assaulted, although part of her clothing was removed.

Police have repeatedly stated that a sun-tanned man, aged between 35 and 40 years old, was vital to the inquiry.

He was seen by two witnesses driving a blue car and speeding down the drive of Aeolian House at about 5pm on the day of the murder, close to the time Mrs Heron was killed.

One witness gave police an excellent description of the man, but could not specify the type of car he was driving or the registration number.

Despite countless appeals, the driver of the car has never come forward.