Conor Murphy's public apology to the parents of Paul Quinn - for branding him as a common criminal and effectively exonerating the brutal IRA mob who beat him to death - is vindication for a mother's enduring love for a child brutally taken from her in the prime of his life.
As in the case of so many other families who have sought justice for loved ones murdered at the hands of the Provos, Breege Quinn found herself confronting a powerful and perfidious political entity with a proven record in silencing detractors.
The bravery of Breege and her husband Stephen cannot be exaggerated as they campaigned for the past 13 years against the republican movement - which dominates every aspect of life around them in the lawless zone of South Armagh, where the IRA Army Council reigns supreme.
Paul Quinn signed his own death warrant when he stood up to some of the bully boys in Cullyhana: like the Mafia, the 'Rafia' does not tolerate disrespect or defiance.
As the political face and apologist for the organisation, Sinn Féin enjoyed huge success swatting away troublesome people like the Quinns by either ignoring, denying, demonising or dismissing them.
With polling day in sight, it seemed that the well-honed practice of dodging bullets and deploying diversionary tactics worthy of Donald Trump had served Mary Lou McDonald and her party well. They were romping home with record levels of public support.
But they hadn't reckoned on Breege Quinn going public and gaining traction with her demand for an apology from Conor Murphy for his slur against her son, something that she has repeated over and over for 13 long years.
Sinn Féin first fell back on the default position by attempting to deny or diminish the mother's demand. McDonald told RTÉ's Bryan Dobson she believed that Murphy had not said those things.
Murphy had also previously denied that he ever said those words, but was exposed as a liar in comments which had been recorded in an interview with BBC 'Spotlight'.
And so we witnessed the spectacle of a leading republican being forced into a humiliating volte-face after years of denials.
This controversy has come as a huge shock to Sinn Féin as it casts an unwelcome light on the dark and shadowy forces that control every aspect of the republican movement - above the heads of its elected representatives, from behind the scenes.
The party's attitude to the rule of law and the sins of the past have proved to be its Achilles' heel.
The only time that Mary Lou McDonald appears inarticulate, fumbling and vague is when she is hit with awkward questions about the likes of the Paul Quinn murder and the party's goal of abolishing the Special Criminal Court.
Listening closely to her responses to these issues over the past week in the leaders' debate and other interviews, one is left with the distinct impression that Mary Lou is answerable to a higher power and that sure isn't God.
Shutting down the country's most powerful weapon against organised crime - which blights the same working-class neighbourhoods where Sinn Féin gets its support - was a central plank of its manifesto.
Then came an act of shocking savagery in the Drogheda gang feud.
Sinn Féin then quickly decided they would have the anti-Mafia court "reviewed".
The backroom men who control the party will never give up their ambition to shut down the court that convicted so many of them in the past, so the "review" will continue until the proponents of the long game decide to have another go when they control the southern government.
And the same shadowy figures will never forgive a loving mother for having the temerity to take them on.