THIRTY years after the events of summer 1982, it is hard to conjure up the sense of shock that gripped the country at the time.
Not only did Malcolm Macarthur -- a once rich, foppish, bow-tied socialite and economics graduate -- brutally bludgeon an innocent woman, Bridie Gargan, to death, he followed this up by shooting dead an Offaly farmer, Donal Dunne.
To add to the shock, the double killer was then found in the home of his friend, the Attorney General, Patrick Connolly.
If he had not been arrested then, who knows where his violent spree would have ended?
Detailed planning notes of Macarthur's, found in a suitcase after the murders, led investigators to believe he had also plotted to electrocute his mother.
In his book, 'Guilty', Stephen Rae (now editor of the Irish Independent) told how the notes carried diagrams and drawings showing how to wire up an electric fire so that it would administer a fatal shock.
Macarthur's vicious killing spree had begun on July 22, three weeks before his arrest.
A son of wealthy Meath landowners and a graduate from the University of California, Macarthur was living with his girlfriend Brenda Little and their son Colm in the Canary Islands.
He returned home to Dublin in early July, because he was desperately short of money.
Having squandered an inheritance of over £100,000, the 36-year-old embarked on a crazy project to copy the IRA and take part in armed robberies. To put his plan into practice he needed a car and a gun. Walking through the Phoenix Park, he saw an opportunity.
Bridie Gargan, a 29-year-old nurse at St James's Hospital, had just finished her shift. She parked her Renault 5 in the park, and lay down in the sun. Macarthur had come prepared for violence. He carried a lump hammer, a crossbow that he had moulded into a fake pistol, and a spade.
He approached Bridie, pointed the fake gun at her and told her to get into the back of the car. She got into the back, but according to Macarthur's account to gardai, she panicked. He took out the hammer and struck her across the head.
Macarthur and his victim were spotted by the driver of an ambulance as it raced out of the park. Seeing a bloodied Bridie Gargan holding her head in the back and a hospital sticker on the windscreen, the crew assumed Macarthur was a doctor, and in one of the many bizarre episodes in the case, the ambulance then gave Macarthur an escort.
When they reached St James's, the murderer then sped off in the direction of Rialto, and abandoned the car with the wounded nurse in it.
Macarthur was still determined to carry out his plan and travelled to Edenderry, Co Offaly to buy a shotgun off the farmer Donal Dunne.
Mr Dunne took him to a bog road that was regularly used by a gun club for clay pigeon shoots.
The farmer gave Macarthur the gun. Macarthur fired at a target. He then turned to his victim and said: "I'm sorry old chap" and blasted him in the face. Macarthur then drove back to Dublin in the farmer's Ford Escort after hiding the body in bushes.
Detectives linked the two murders, because Macarthur had taken the victim's car in both cases.
Suspicions the killer was in the Dun Laoghaire area were heightened when Macarthur tried to rob Harry Bieling, a retired US diplomat. Macarthur then hailed a lift to Pilot View, Dalkey, and called in at the home of his friend Mr Connolly, who invited him to stay without knowing what had happened.
MacArthur's biggest blunder came on the following day when he phoned Dalkey garda station, giving his own name, to say the incident involving Mr Bieling had been a prank. It did not take long before gardai found Macarthur in Pilot View. Of course, Mr Connolly was entirely innocent in the matter, but he did nothing to dampen the sense of panic that overcame the government by continuing with plans to go on holiday in the United States. He was called back by the Taoiseach Charles Haughey and resigned.
Mr Haughey described this series of events as "Grotesque, Unbelievable, Bizarre and Unprecedented" -- leading the columnist and former cabinet minister Conor Cruise O'Brien to coin the acronym GUBU.
The trial of Macarthur (pictured, left, in 2011) caused outrage. His appearance at the Central Criminal Court in January 1983 took only five minutes and no evidence was heard.
He pleaded guilty to the murder of Ms Gargan; but he was not tried for Mr Dunne's murder as the state did not proceed with a prosecution. He received a life sentence for the Gargan murder, and after serving 30 years in jail, he was released on Monday morning.