MAJOR new developments in genetic testing could hold the key to solving a ten-year murder in Darlington.

Detectives hunting the killer of Ann Heron have confirmed that a series of new DNA tests are to be carried out on the exhibits collected during the investigation.

They are hoping for a breakthrough in the inquiry, which began when Mrs Heron was found with her throat cut in her home on the outskirts of Darlington on August 3, 1990.

Supt John Blake, the detective in charge of the inquiry, said a review of all 1,500 exhibits has been carried out and a small number are to be sent to forensic scientists who will carry out new DNA tests.

They include a series of taunting letters, in which the author claimed he was the killer, which were sent to The Northern Echo, Mrs Heron's husband, Peter, and police.

Supt Blake said the investigation team and scientists have been monitoring advances in DNA profiling and it has now been decided, on the tenth anniversary of the murder, to begin a new series of tests.

He said: "We have been patiently waiting for the right time and the right technology and we believe the time is now.

"I am hopeful the tests, which will take months to complete, will not only eliminate some people from the inquiry but will, more importantly, point us to the killer."

Mrs Heron's bloodstained body was found by her husband in the couple's isolate home, Aeolian House. Her killer had slashed her throat in what detectives believe may have been a sexually motivated attack.

Police were frustrated in attempts to track down a sun-tanned man, aged 35 and 40, who was spotted by two witnesses driving a blue car at speed down the drive of Aeolian House at around 5pm, the time when Mrs Heron is thought to have been killed.

Supt Blake remains convinced there are still people in the Darlington area who have information crucial to the investigation.

Police can be contacted on (0191) 3864929 or (01325) 467681