Sinn Fein leader Gerry Adams has apologised for the IRA killing of Detective Garda Jerry McCabe 17 years ago.
The officer was gunned down by republicans during a botched post office raid in Adare, Co Limerick, in June 1996.
Anne McCabe had previously challenged Sinn Fein to apologise for her husband's death
Mr Adams apologised on Tuesday for the attack in the Irish parliament as he paid tribute to another officer shot dead during a robbery in his constituency last Friday.
He told the Dail the death of Detective Garda Adrian Donohoe had provoked memories of the killing of Gda McCabe and the wounding of his colleague, Garda Ben O Sullivan.
"I want to apologise to Mrs (Anne) McCabe and the McCabe family, and to Garda Ben O Sullivan and to the families of other members of the state forces who were killed by republicans in the course of the conflict," said Mr Adams.
"I am very sorry for the pain and loss inflicted on those families. No words of mine can remove that hurt. Dreadful events cannot be undone.
"But I want to restate that the resolve of Sinn Fein and of the majority of Irish people is to ensure that there is never ever a recurrence of conflict."
Four Provisional IRA members were later convicted of killing the detective, but have since been freed from jail.
Ten years ago Mr Adams described the murder of Det Gda McCabe as reprehensible, but did not apologise. The garda's widow had publicly challenged him to condemn her husband's killing.
Separately Sinn Fein's Martin McGuinness, Northern Ireland Deputy First Minister, was confronted by the son of an Irish solider killed in an IRA shoot-out.
David Kelly's 35-year-old father Patrick was shot dead with trainee garda Gary Sheehan, 23, at Derrada woods near Ballinamore, Co Leitrim, during the rescue of kidnapped supermarket tycoon Don Tidey in 1983.
Mr McGuinness, who was challenged while canvassing for the Irish Presidency in 2011, was forced to deny knowing the names of the IRA members involved and of being on the IRA army council.
Meanwhile Mrs McCabe this week called for tough mandatory sentences for anyone convicted of murdering a member of the force as she signed a book of condolence for the late Gda Donohue at Limerick Garda Station, where her husband was based.
The 41-year-old garda, who was shot dead at a rural credit union less than two miles from his home in Lordship, Co Louth, will be buried tomorrow.
Mr Adams, who was elected as a TD in Louth two years ago, extended his deepest sympathies to the family, friends and colleagues of Det Gad Donohoe.
He said the killing has shocked the entire community, especially in the very closely knit Cooley area and South Armagh.
"Members of An Garda Siochana do a dangerous job," he continued.
"They take risks for all of us. Adrian Donohoe showed great courage when he confronted armed criminals at Lordship. He died in defence of other citizens.
"I want to appeal to anybody with any information about this crime to co-operate with the Garda or the PSNI."