The two men jailed for the 1996 manslaughter of Irish police detective Jerry McCabe, 52, were released from prison in Limerick today.
The men, who were both members of the Provisional IRA, had no comment to make as they were driven away in a van.
Walsh and McAuley were among four men who were jailed for the manslaughter of Detective McCabe who was shot several times at close range during an armed raid on a post office van in Adare, Co Limerick.
His death sparked outrage in Ireland and more than 25,000 people lined the streets in Limerick for his funeral.
Sinn Féin President Gerry Adams today issued a statement saying the two men had expressed their "deep regret and apologized" to the families of Detective McCabe and another police officer, Ben O'Sullivan, who was injured in the raid.
Mr Adams said the apology was "genuine" and that it echoed the "sentiments of republicans everywhere."
He said he deeply regretted the "great loss and hurt suffered by the McCabe and O'Sullivan families."
Walsh and McCauley both served out their full sentences despite being eligible for early release under the terms of the Good Friday Agreement.
The Irish government said the killing was a special case and the Irish Supreme Court upheld the government's decision.