Hope has been expressed that advances in forensic science may help the investigation into the killing of three police officers in a 1982 IRA bomb attack.
Sergeant Sean Quinn, 37, and Constables Paul Hamilton, 26, and Allan McCloy, 34, died in the blast at Kinnego Embankment in Craigavon, close to Co Armagh beauty spot Oxford Island, on October 27.
They had been responding to a call when the explosion flung their unmarked Ford Cortina 70ft (21m) into a nearby field.
The blast left a huge crater in the road and witnesses described seeing two people running away from the scene.
Despite various investigations and nine arrests, no-one has ever been charged with the murders of the three officers.
The men’s families have said they had given up hope that the crime would ever be solved, but have now been encouraged by recent progress.
It comes after the case became the latest to be taken on by former Bedfordshire Chief Constable Jon Boutcher as part of Operation Kenova, a series of legacy investigations.
Speaking on the 38th anniversary of the murders, Mr Boutcher urged anyone with information to come forward.
Images of two helmets, which those responsible were believed to have been wearing as they fled on a motorcycle, have been released to help jog memories.
The bike was later abandoned in Francis Street in Lurgan.
“The explosion came during a period of sustained bombings, but I have no doubt that the identity of those involved will be well known to some,” said Mr Boutcher.
“We have made huge strides forward in forensic technology in the years since this happened, and Kenova are exploiting all the opportunities, which were not available to previous investigations.
“We have made encouraging progress, but we still need people to come forward to help us complete the jigsaw and give the families of these three officers the answers they so desperately need.”
Mr Boutcher went on: “If people saw those responsible, notwithstanding that it was such a long time ago, I am sure they will still remember it well, because they will have soon realised just what an evil act those men committed that day. Help us to help these families.
“If you have any information about this awful incident, please do the right thing. Come forward and speak to us.”
The three RUC officers were killed instantly in the blast which was caused by a landmine.
Three women were widowed, five children grew up without their fathers, and an unborn son never got to meet his father.
Kellie Morwood, a solicitor acting for the families, said anniversaries are always difficult for them.
In the statement, the families said they have had 38 years without husbands, fathers, sons and brothers, and also without justice or closure.
We would echo the appeal made by Mr Boutcher and ask those people who know anything about the attack to come forward to help deliver some closure for usBereaved families
“Never a day passes but we think of Sean, Allan and Paul,” they said.
“Our loved ones were doing their duty as RUC officers by responding to a report of a robbery when IRA terrorists detonated a landmine under their car.
“In a single moment of barbaric carnage, faceless cowards changed our lives forever.
“For a long time, we believed this appalling terrorist crime would remain unsolved.
“Now, however, with ‘encouraging progress’ achieved, we have been given renewed hope that the culprits will be identified, and with that we will have achieved a sense of closure that has eluded us for far too long.
“We would echo the appeal made by Mr Boutcher and ask those people who know anything about the attack to come forward to help deliver some closure for us.”
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