by Malcolm Prior BBC News, Berkshire

Mrs Pemberton had long been a victim of domestic abuse

Mrs Pemberton and her 16-year-old son William were shot dead by her abusive husband in November 2003.

The horror of the deaths has driven Mrs Pemberton's brother, Frank Mullane, to try to prevent other such tragedies.

His efforts have already won an agreement, the first of its kind in the UK, to hold a review of the deaths to help shape future investigations.

We will not sign up to a whitewash or anything short of something that will help stop these murders Frank Mullane

Mr Mullane, from Swindon, Wiltshire, is due to go to the High Court on Wednesday to fight for an overhaul of how the review will take place, before it has even got under way.

But the 44-year-old makes it clear he is not out to cause trouble, just to ensure that the probe brings real change.

He told the BBC News website: "We are not in it to be adversarial. We are not in it for retribution, or to beat anyone up over it.

Police delayed entering the house for several hours

"The family want to be seen as progressive. We want to create change.

"But we will not sign up to a whitewash or anything short of something that will help stop these murders."

Julia and William Pemberton were killed at their home in Hermitage, near Newbury, Berkshire.

Mrs Pemberton's estranged husband Alan, 48, then turned the gun on himself.

At the time of the tragedy, Mr Pemberton was already the subject of a court order banning him from going anywhere near the family home.

At the inquest, which heard the transcript of Mrs Pemberton's 999 call, East Berkshire coroner Peter Bedford recorded verdicts of unlawful killing and said police could not have prevented their deaths.

Something is broken and it needs fixing Frank Mullane

But Mr Mullane has always claimed the murders only came after a series of incidents which he believes should have been recognised as clear alarm bells.

Early last year, Home Office minister Baroness Scotland asked Thames Valley Police to hold a formal homicide review into the tragedy.

Originally set to begin last October, the inquiry was put on hold when Mr Mullane began legal action to widen its remit.

He wants a judicial review of its scope, to make sure his family - and other families in the future - can have their say, and provide vital information.

"Families have information and insights about the various compromises victims of domestic violence have to make.

Independent witnesses

"We could give insights into how Julia felt about the agencies' response. We could help them see the red flags, the larger risk indicators.

"We know two women get killed every week in England and Wales and we feel we have a duty to use our experience to help bring about change."

Mr Mullane also hopes the High Court judge will back his desire for more independent witnesses to give evidence at the review.

He insists that, if successful, the review will help identify "clusters" of abuse cases where indicators of a possible tragedy could be found.

He does, however, remain realistic, saying he is "clear that we cannot protect all of (the victims)" before simply adding: "But we believe something is broken and it needs fixing."

A spokeswoman for the review's commissioners - the West Berkshire Safer Communities Partnership, which includes police, the local authority and other agencies - declined to comment ahead of the court hearing.