The Troubles: Memorial for RUC officer killed in Republic of Ireland

John Doherty was 31 and based in Omagh, County Tyrone when he was murdered

A memorial is to be unveiled to the first Royal Ulster Constabulary (RUC) officer killed in the Republic of Ireland during the Troubles, 50 years after he was shot.

John Doherty was ambushed by the IRA while visiting his widowed mother near Lifford, just across the border.

A new memorial stone with the RUC crest will be unveiled at Castlefinn cemetery where he is buried.

Family, friends and former colleagues will attend the event.

John Doherty was a 31-year-old single Catholic man who was part of the CID team based in Omagh in County Tyrone.

On the 28 October 1973 he crossed the border to visit his widowed mother Annie at the family home at Ballindrait near Lifford.

He and his girlfriend were targeted by an IRA gang at 20:40 GMT as he turned his car in a narrow laneway.

His mother rushed out and found him lying in the car.

"You never get over it especially when you didn't see justice" - Terry Doherty

His brother Terry Doherty said it was a devastating loss.

"You never get over it especially when you didn't see justice," he said.

"You have to live with it and remember John for who he was and what he represented.

"I am proud of the fact that John served with the RUC, served the London Metropolitan [Police] and I served with the Irish Army for nearly 27 years."

John had served in the Metropolitan Police for two years before returning to Northern Ireland in 1969 as the Troubles broke out.

He was first stationed in Belfast and then in Omagh.

His girlfriend survived the attack - which Terry described as a miracle.

Nobody was ever convicted for his killing.

John was visiting his mother Annie when he was killed

"The family were very close and I think it was John's love of the family and especially of our widowed mother that he actually visited the home and sadly he paid the price for that," Terry said.

"My mother was first on the scene.

"There's a big family. Originally there was eight boys and six girls of the family in a little cottage not far from Ballindrait.

"On the night that John was murdered there was only my mother and two sisters at the house. The way it worked out was unbelievable.

"I must say that our parents had very strong faith and everybody should be respected for their faith and their religion regardless what church they attend.

"I think it was her faith - definitely her faith - that got her through.

"She saw so much and went through so much. Its hard to believe that before she passed away in 1997 she had laid to rest five sons before she was laid to rest herself."

John Doherty's brother William says his death was a "fierce loss"

The Doherty family have been preparing for a special service where the memorial stone will be dedicated.

John's brother William, for whom he was best man, said it was a "fierce loss".

"It's a loss you never can explain. A loss that you will never ever forget," he said.

John Doherty enjoyed life to the full, his brother said

"As a brother he was everything. It didn't matter what you wanted or where you wanted to go he was always there at hand to take you and nothing was any trouble to him.

"As a brother he was just everything. He was really fun to be along with.

"He'll never ever be replaced, ever. But you'll never forget the memories.

"And when you look back they are great memories to have now. Justice never was done.

"You are always angry to a certain extent that justice wasn't done and when you look at other families the way they've suffered - you suffer along with them as well.

"You just don't suffer on your own. Your whole family suffers along with you."