Nicola Tallant reports on the triple tragedies of the Reavey and O'Dowd family murders as well as the Kingsmills Massacre.
Forty-six years ago, 16 innocent victims lost their lives in the south Armagh murder triangle in a 24-hour period of wholesale slaughter.
The killings have become a case study in mass murder.
Sunday World crime editor Nicola Tallant recently visited south Armagh to hear the story for herself.
Nicola met up with south Armagh farmer Eugene Reavey, who talked her through the night sectarian murder called to his family home at Whitecross.
Gaelic footballer-playing brothers John Martin (24), Brian (22) and Anthony Reavey (17) were shot at they watched Celebrity Squares on TV.
"It may have been 46 years ago. But when I think about it now, it all comes flooding back to me as though it was yesterday," said Mr Reavey.
He added: "If playing Gaelic was a crime, then we were all guilty."
It later emerged the Reavey boys had been gunned down by members of the 'Glenanne Gang', made up of UVF men and serving members of the security forces.
Eugene tells Nicola how a "burly" gunman came into the unlocked front door and opened fire.
"He just cut John Martin in two nearly - there were 40-odd bullets in him. Brian got shot in the back - it went right through his heart, so they were very professional people who were doing this shooting.
"Anthony had dived under the bed and the gunman followed him up and fired 30-40 rounds into the bed. Seventeen bullets hit Anthony but didn't kill him.
"Anthony heard this car pulling up and the footsteps of the gunmen running to the car. He crawled out from under the bed - there was some trail of blood - and he managed to crawl on his hands and knees up to the neighbour's house and you could follow the blood the whole way up."
Tragically, Anthony died in hospital two weeks later.
Just 10 minutes after the Reavey brothers were shot on January 4 1976, UVF terrorists Robin Jackson and John Somerville entered the home of the Catholic O'Dowd family at Ballyduggan, near Guildford.
A family sing-song was under way around the piano when 24-year-old Barry O'Dowd was shot dead.
The UVF men continued to spray the room with automatic gunfire and Barry's 19-year-old brother Declan and his uncle Joe were also killed.
Around teatime the following day on Monday January 5 1976, a minibus taking linen factory workers home after a day's work was stopped near Kingsmills Crossroads, around a mile from the Reavey home. Heavily armed men ordered the workers out onto the side of the road. And after singling out the driver who happened to be a Catholic and ordering him to leave, they gunned down the rest.
Ten innocent Protestants died at the scene, while Alan Black - another entirely innocent man - survived despite being hit by 18 bullets.
The IRA was responsible, but using a phony flag of convenience, the republican terror group attempted to avoid responsibility for its actions.
The South Armagh Republican Action Force claimed it had carried out the shocking crime.
As the IRA murder gang escaped into the night, Eugene Reavey and other members of his family set out from the family at nearby Greyhilla to retrieve the bodies of his two dead brothers from the hospital morgue at Newry's Daisy Hill Hospital.
As his car approached Kingsmills Crossroads, Eugene thought he saw injured cows lying on the road.
And it was only when he drew nearer he realised he was looking at dead human beings.
"It was teatime in early January, so it was very dark. I thought some cows had escaped from a field and had been struck by cars. Then it dawned on me these were human beings. They were people. It was appalling. It was an awful thing to see and the thought of it will haunt be for the rest of my life." Eugene tells Nicola.
The workers who lost their lives at Kingsmills were Robert Walker (46), Joseph Lemmon (46), Reginald Chapman (25), Walter Chapman (23), Kenneth Worton (24), James McWhirter (58), Robert Chambers (19), John McConville (20), John Bryans (46) and Robert Freeburn (50). All of them were Protestant and were being driven home from work in a linen factory at Glenanne.
Eugene Reavey also spoke about how his now deceased mother Sadie was devastated when she was told DUP leader Ian Paisley had used Parliamentary Privilege to claim that Eugene was involved in the Kingsmills attack.
"My mother was stunned into silence by Ian Paisley's remarks," he said.
"She told a reporter who spoke to her afterwards what it was actually worse than losing her three sons.
"My mother was genuinely appalled to think anyone might believe Paisley and think members of her family had been involved in such a horrific thing as Kingsmills," said Eugene.
Within hours of the DUP leader's remarks though, the then Chief Constable of the RUC Sir Ronnie Flanagan issued a public statement rubbishing Paisley's bogus claims.
It later emerged Paisley had been handed a forged intelligence report. And he had used it as the basis of his House of Commons claims.
The document had been given to Paisley by the now deceased loyalist activist and self-confessed loyalist paramilitary gunrunner Willie Frazer.
Despite repeated requests, Ian Paisley went to his grave without withdrawing the claim, although the Reavey family were successful in having the House of Commons record amended.