Murder cops have today pledged their 'ambition' to solve a baffling unsolved murder case, as the victim's family ask for a new force to be put in charge of the probe.
It has now been 31 years since Ann Heron was killed at her home in Darlington, but to this day no one has been brought to justice for her murder.
Ann's husband Peter, who found her body, was arrested and charged with her murder in 2005 after cold case detectives re-opened the investigation.
Read more: Ann Heron murder: Could this new evidence hold the key to solving murder mystery?
The case against him was later dropped due to a lack of evidence.
Earlier this year Peter's daughter Debbie Simpson's lodged an official complaint against Durham Constabulary over the force's handling of the case and her dad's arrest.
The force responded this week, and solicitors acting on behalf of Ann's family say they will now go to the Independent Office for Police Conduct (IOPC)to ask for an independent investigation into the murder and Durham Constabulary's probe.
However, a spokesman for the force said detectives were still committed to doing all they can to convict Ann's killer themselves.
A spokeswoman for Watson Woodhouse Solicitors, who are representing the family, said: "Ann Heron's family has received a response from Durham Police who have responded negatively to the concerns of the family in the Ann Heron Case.
"They say they have conducted a forensic review of the case by a Det Chief Supt and that lines of enquiry will be or have been pursued where there has been new information.
"The family cite concern that Durham Police are investigating themselves and they have not addressed the failings in the initial investigation.
"The matter needs to be subject of an independent objective investigation which can only be done by either by an outside force or the IOPC.
"Alistair Smith, defence solicitor at Watson Woodhouse, will be responding to the Durham Constabulary response by writing in these terms to the IOPC this week."
But a Durham Constabulary spokesman said: "The murder of Ann Heron has been thoroughly investigated and subject to constant review over the last 31 years, including the use of new investigative techniques with the advancement of forensic technology.
“It is still the ambition of Durham Constabulary to convict the person responsible for Ann’s murder.
“At this time there is no new evidence that identifies new suspects, but we remain open-minded.”
Ann had her throat cut at Aeolian House, on the outskirts of Darlington on August 3, 1990. The mum-of-three had been sunbathing in a bikini on the hottest day of the year. Her body was found in a pool of blood by Peter, a haulage firm operations manager, when he returned home.
Although colleagues confirmed that Peter had been at work a mile away when Ann was killed, he was arrested and charged in 2005
The finger of suspicion was pointed at him soon after the murder as police discovered he had been having an affair with a barmaid at his golf club.
And new DNA techniques found Peter’s DNA on Ann’s body. But the case collapsed before it went to trial due to lack of evidence.
Debbie's six page complaint to Durham Constabulary highlighted what the family believes to be failings in the original investigation, and seeks answers to a number of questions.
Debbie, 59, also wants her father's name to be cleared fully.
