A number of lines of inquiry are being investigated by Gardai after a review of the investigation into the 1972 Belturbet bombing that killed two teenagers.
The families of the victims welcomed the “significant” development, and urged anyone with information to come forward.
A car bomb exploded outside Farrelly’s Bar and McGowan’s Drapery on the main street of Belturbet in Co Cavan after 10pm on December 28 1972, killing Patrick Stanley, 16, and Geraldine O’Reilly, 15, instantly and leaving eight others injured.
In a statement issued on Wednesday, gardai said a senior officer has been appointed to lead the investigation with an incident room at Ballyconnell Garda Station.
We have supported the two families for almost 20 years and, at last, we have this very significant and positive development in the case— Pat Finucane Centre
The Pat Finucane Centre, along with the O’Reilly and Stanley families, welcomed the development and urged people to come forward.
The human rights group said the teenagers had lost their lives in a no-warning loyalist bomb attack, adding: “We have supported the two families for almost 20 years and, at last, we have this very significant and positive development in the case.
“We appeal for anyone with information to contact the Gardai,” it said.
Patrick, from Clara in Co Offaly, was a keen hurler, footballer and soccer player.
He had applied for a cadetship in the Army but was temporarily employed by local businessman Pat Jennings as a helper on a Calor Gas delivery lorry.
On the night of the explosion there had been a problem with the lorry, meaning he and the driver decided to stay in Belturbet overnight.
When the bomb exploded, Patrick was in the public phone booth on the main street calling his parents Teresa and Joe to tell them he would not be home.
Geraldine was from Drumacon in the Belturbet area, and the youngest of seven. She had completed her Group Certificate examination the previous June, gaining six honours and intended taking up a career in nursing.
She had come into town with her brother Anthony to get food, and was in a restaurant when the bomb exploded in a car parked opposite.
Solicitor Kevin Winter welcomed what he termed “an extremely positive move by the Gardai”.
“I commend the patience and determination of the families in continuing to fight for justice and closure for the loss of their children,” he said.
“This news will also support pending civil proceedings in the High Court in Belfast.
“We represent each of the families in ongoing claims for damages for collusion in relation to intelligence issues connected to the killers and the state.
“The case is on all fours with a series of other similarly themed claims, all of which point to serious investigative failures by the authorities in the North on Troubles-related incidents in the Republic of Ireland.”
The incident room at Ballyconnell Garda Station can be contacted on 049 9525580, the freephone Garda Confidential Line on 1800 666 111 or Crimestoppers can be contacted on 1800 250025.