Two potential witnesses come forward in murder inquest for policeman Joseph Campbell

Sergeant Joseph Campbell was shot dead outside Cushendall RUC station in February 1977.

The policeman's family believe elements of the security forces colluded with now deceased UVF killer Robin Jackson to shoot dead the 49-year-old father of eight.

It has been alleged that Mr Campbell, a Catholic officer originally from the Republic of Ireland, was potentially targeted because he had uncovered a loyalist arms smuggling operation.

A second inquest into the shooting, which the family has long campaigned for, began hearing evidence in March at Belfast Coroner's Court.

It has since adjourned to allow further time for disclosure and security vetting of historical police and military files related to the killing.

A review hearing was held before coroner Patrick McGurgan in Belfast on Friday.

In February, Mr McGurgan issued an appeal for anyone who believed they could assist the inquest to contact the Coroners Service's Legacy Inquest Unit.

Investigators from the unit held a clinic at the parochial hall of St Mary's Church in Cushendall in the same month to give people an opportunity to come forward.

Counsel to the coroner Ronan Daly updated the court on the initiative on Friday.

"As you know, a witness clinic was held in Cushendall on the 28th of February," he told Mr McGurgan.

"As I understand it, nobody attended the clinic, but there was some contact afterwards."

The barrister added: "Two potential witnesses contacted your office and arrangements are being made for those individuals to be interviewed."

In 2014, an investigation by the Police Ombudsman found RUC Special Branch was aware of a threat against Mr Campbell but failed to inform him.

The Ombudsman also identified a series of investigative failings by the police.

However, the Ombudsman was unable to substantiate claims that rogue security force members conspired with loyalists to commit the murder.

A former RUC Special Branch officer, now deceased, was charged with Mr Campbell's murder but was later acquitted at trial.

The first inquest in 1977 lasted only one day.

A fresh inquest was ordered by the attorney general seven years ago.

The substantive hearings in the case are not expected to resume until next year.