DETECTIVES investigating one of Britain's most baffling murders say a breakthrough could be "just around the corner".

Ann Heron, 44, was found lying in a pool of blood at her home on the outskirts of Darlington, 11 years ago today, on August 3, 1990.

With continued strides in forensic science since the killing, Superintendent John Blake, who is leading the investigation, remains confident, yet frustrated, that the man responsible may still be on the loose.

"It is frustrating but I have to remain patient," he said last night, the eve of the anniversary.

"There have been tremendous advances in DNA profiling in recent years, which are still going on at a pace. While I do not want to raise false hopes, I remain confident the scientists will give us the vital lead we need."

Mrs Heron's bikini-clad body was found by her husband, Peter, when he returned home to Aeolian House, just off the A67, near Morton Palms, in the early evening. She had spent part of the afternoon sunbathing in the grounds of the house.

Her throat had been slashed in what detectives believe was a sexually-motivated attack.

In late 1999, more than 1,500 exhibits collected from the scene were reviewed and a small number have been earmarked for delicate re-examin-ation in Home Office labs using the latest DNA techniques.

This will "ultimately yield that critical new piece of information we have been searching for", said Supt Blake.

"Time has done nothing to dilute our determination to catch the man responsible," he vowed.

"There has been no let-up in this investigation and nor will there be. But just one telephone from the person or people who we believe has been shielding the killer, could end it," he said.

Supt Blake praised the public's continued willingness to help at every step.

Aeolian House has recently been bought from Mr Heron, who wants to start a new life in Scotland with his new wife.

Andrew and Louise Bloomfield, from Yarm, near Darlington, have received outline planning permission from Darlington Borough Council to turn the house into an animal training centre and pet crematorium.

Mr Bloomfield said last night he hoped to start work transforming the site on August 31.

Planning officers will use delegated powers to finalise the details.

Anyone who has any information on the murder is asked to contact the Holmes Room at Durham Constabulary headquarters, on 0191-386 4929.