Police have unlawfully given up pursuing a lead on the suspected brutal and unsolved murder of a north Belfast woman 47 years ago, the High Court heard.

Counsel for relatives of Rosaleen O’Kane claimed the PSNI has failed in its legal duty to probe information naming three individuals potentially involved in a death described as a “whodunit mystery”.

Desmond Hutton KC argued: “It’s not unreasonable to say this whole thing is a disgrace, the way the family have been treated.”

Ms O’Kane’s badly burnt and naked body was discovered at her Cliftonpark Avenue flat in September 1976.

Although an autopsy failed to reveal the cause of death, the 33-year-old had a fractured skull and more than one seat of fire was located in the apartment.

Her family believe she may have been killed by a loyalist paramilitary gang targeting innocent Catholics in the area at the time.

Following Ms O’Kane’s funeral, two police officers allegedly indicated that she had been murdered.

It was even suggested that ‘black magic’ may have been involved.

No-one has ever been prosecuted for her death, but in 2002 police informed relatives that a re-investigation was to be carried out.

Since then, the case has been passed from the Historical Enquiries Team to the PSNI’s Serious Crime Review Team and then the Legacy Investigations Branch (LIB).

Ms O’Kane’s sister, Kathleen Graham, is seeking to judicially review the PSNI over an alleged unlawful failure to fully probe her suspected murder.

Her lawyers claimed the force had breached an obligation under Section 32 of the Police (Northern Ireland) Act 2000 to detect crime and bring offenders to justice.

At the centre of the challenge is information provided to detectives back in 1976 by an unidentified man referred to as KW1.

He claimed three other individuals had been engaged in activity in the north Belfast area which was “suspiciously like” the incident which caused Ms O’Kane’s death.

Mr Hutton argued that in 2002 police identified a need to speak to KW1 but failed to do anything about it.

“This is a step that would have progressed down the path to identifying the perpetrators,” he insisted.

With checks confirming that KW1 died in 2011, an assessment was made that nothing more could be done about his statement.

“It seems that police are effectively giving up,” Mr Hutton contended.

“All this time, all these opportunities and various police departments have identified the need to progress the case, and they just haven’t done it.”

He added: “On no planet could that be in compliance with the duty. This cannot be right.”

In an affidavit Ms Graham described the distress endured by the family and her fear that those identified as allegedly setting fire to the flat will never be questioned about their actions.

She also expressed dismay at the prospect of dying before the truth about what happened to her sister is established.

Tony McGleenan KC, for the chief constable, countered that police are dealing with 1,100 legacy cases requiring operational choices based on resources.

Acknowledging some “unsatisfactory aspects” in the initial handling of Ms O’Kane’s death, he detailed other investigative steps taken since 1976.

Consideration was given to exhuming and examining the body, but pathologists decided there was little to gain from it.

According to Mr McGleenan, attempts were also made to engage with a man who named another individual as potentially involved in the death.

“It cannot be seriously said there was no investigation, or there was a complete abdication of the obligation to investigate,” counsel submitted.

“The history of this case is tied up with the unfortunate history of the legacy investigation process in this jurisdiction. It involves wider policy choices.

“It will in due course be reached, subject to other statutory interventions in respect of the investigation of these sorts of cases.”

Reserving judgment, Mr Justice Humphreys pledged to rule on the challenge as soon as possible.