On the evening of March 9, 2009, Constable Stephen Carroll (48) was shot dead as he was responding to an emergency call in Craigavon - a distressed woman had contacted police to say her home was under attack. The attack had been staged by the Continuity IRA to lure police into the area. Constable Carroll's death was yet another sad milestone in the misery inflicted by paramilitaries in Northern Ireland. He was the first member of the PSNI to be murdered.
There, in a couple of sentences, are the stark factual details of what happened that terrible night.
But the full devastation wreaked by those two bullets which claimed Stephen Carroll's life is immeasurably harder to express. As with all Troubles killings, it is the family and friends of the slain who have to try to piece their own lives back together. The rest of us, we really only glimpse at their grief and their loss, their heartache and their struggle to keep going.
Right from the start Kate Carroll, Stephen's widow, was determined that his memory should be kept alive. She was equally determined to do what she could to speak out and try to ensure that other families would be spared the same pain.
Down the years she has become a well-known face on television and in the newspapers.
Kate is, just as she comes across in interviews, a lovely, warm, caring woman. She is the first to ask how everyone else is. And as much as she is kind and compassionate, she is courageous. She has been fierce in her denunciation of violence and the violent. And fervent in her desire for reconciliation.
Above all Kate has wanted people to see the awful legacy of murder, to give some insight into how it leaves its malign stain forever.
There is a chilling but very true line about how the bullet that claims a life like Stephen Carroll's travels on down through the generations.
It ricochets through other lives leaving other wounds that might never heal.
Today Kate Carroll is mourning the loss of her beloved son Shane who has died tragically at the same age as his stepfather Stephen.
Shane, the father of 10 children, had suffered for many years from depression and mental health issues. His struggles were exacerbated, inevitably, by the cruel murder of the man he loved and looked up to.
It would be simplistic and wrong to ascribe Shane's death solely to his stepdad's killing. But it is not hard to imagine the impact such a brutal loss would have had on his young life. He was a crucial support for his mother, not least during the court cases that ensued.
Shane was by Kate's side in court when the two dissident republicans who murdered Stephen - Brendan McConville and John Paul Wootten - lost their appeal against their convictions. And now Shane's wife Elaine is left a widow too. His own young children are left bereft.
The bullet that passes down the generations...
Kate Carroll has lost her beloved husband and she has lost her adored only son. Heartbreak upon heartbreak. She is a strong woman, Kate. And her partner Derek Egerton who has brought love and joy into her life in recent years will be her bulwark.
But to all of them, to Elaine, to Shane's children, to Kate and Derek, what can any of us say?
Just grieve for them and for the lives lost - and for another generation blighted by unimaginable tragedy.