Families of the victims in the 1971 McGurk’s Bar bombing in Northern Ireland filed a request with Attorney General John Larkin for a new inquiry into the attack, citing evidence previously withheld by the British Army, a lawyer of victims’ relatives said Thursday.

“The recently discovered [British Army] log sheets of the 4th and 5th December 1971… provide clear evidence that the ATO [ammunition technical officer] who examined the scene was convinced from the outset that the bomb had been placed in the entranceway of the pub,” solicitor Padraig O Muirigh said in a press release.

The bomb’s location was a key question in the investigation, with police reports claiming the Irish Republican Army (IRA) had mistakenly bombed Irish nationalists.

Subsequent evidence revealed the attack was carried out the loyalist paramilitary group Ulster Volunteer Force (UVF).

O Muirigh noted there are still questions about whether there was collusion between loyalist paramilitaries and the UK security forces in the bombing.

“None of this evidence was ever presented at the original inquest in June 1972. In fact forensic and witness statements were withheld from the original Coroner,” said Ciaran MacAirt, whose grandmother was killed in the attack.

A 2011 police ombudsman’s report found the security forces had given selective and misleading information to the government and the media indicating the bomb was planted by the IRA.

The bombing at the North Belfast bar, which killed 15 people, was the deadliest attack during Northern Ireland’s decades-long conflict known as the Troubles.