The police complaints watchdog has said it is working as quickly as possible to consider a review of the way Durham Police handled an arrest connected to an unsolved murder in Darlington.

The Independent Office for Police Conduct (IOPC), which said it is "working hard to address a backlog of cases", was responding to criticism they have faced from the family of Peter Heron regarding the handling of their complaint.

Ann Heron was found dead at her Aeolian House home on the A67 near Darlington on August 3, 1990. Her killer has never been discovered.

Her husband, Peter Heron, was arrested and charged in 2005 for her murder. The case was discontinued 12 weeks later, but Mr Heron's family say the damage to his good name and reputation remains and his daughter, Debbie Simpson, has been campaigning to clear his name ever since.

A formal complaint was made to Durham Constabulary's Professional Standards Department, through the family solicitor, in February 2022 alleging 'incompetence and potential malfeasance by the form of falsehood'.

Read more: Ann Heron muder: Daughter says IOPC appeal delay unacceptable

An investigation by the force's own professional standards team cleared it of any wrongdoing. An appeal against this decision was submitted to the IOPC in January this year.

Ms Simpson has criticised the IOPC for what she said were delays in progressing the appeal.

However, the IOPC sad it is expecting to be able to provide the complainant with an update soon.

An IOPC spokesperson said: "We are working hard to address a backlog of cases, which, regrettably, means we are not currently able to provide decisions on reviews and appeals as quickly as we would like.

Read more: Darlington: Fresh appeal to solve Ann Heron's murder

"This work is having an impact – the backlog is reducing and waiting times are down – but there remains more to be done.

"Legislative reforms that replaced appeals with reviews, while improving the complaints process, have led to a substantial increase in both the volume and complexity of work coming into our casework unit.

"Over the last three years we have seen a 33 per cent rise in the total number of referrals coming to us, many of which result in reviews.

"We recognise it is in everyone’s interest for cases to be completed as soon a reasonably possible and that is why significant efforts have been made, which have seen waiting times start to reduce this year.

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"This has included investing in our workforce to increase the unit’s capacity substantially, as well reviewing our internal processes to increase efficiency. And we are now beginning to triage cases to minimise the impact of the backlog on the outcomes of reviews, as well as the individuals involved.

"We have also started working with forces to offer support and guidance to help resolve complaints at a local level as often as possible and get complaint handling right first time.

"We are providing 24-week updates to complainants affected by the current difficulties and keeping forces updated on the progress of this work."