On the night of March 6th/7th, 1997 someone entered the Eastern Health Board sheltered home where three elderly patients, Sylvia Shields, Mary Callinan and Anne Mernagh, lived beside Grangegorman Hospital. Ms Shields was battered and stabbed to death in her bedroom. The same fate was inflicted on Ms Callinan in the adjoining bedroom.
The intruder then went into Ms Mernagh's bedroom. But she was not touched and the killer simply left the house and walked away.
A large-scale investigation was established by the alarmed gardai. A psychologist told detectives they could expect this murderer would kill again, possibly soon.
There was considerable pressure on the investigation team and, after a tip-off from a heroin addict, on July 27th, 1997 they arrested an innocent man, Mr Dean Lyons, and charged him with murdering Ms Callinan.
Twenty-one days after Mr Lyons was charged, Catherine Doyle was stabbed 16 times with terrific force and died along with her husband Carl, who received four powerful stab wounds to his chest as he sat asleep in a chair.
The injuries inflicted on Carl and Catherine bore considerable similarities to those inflicted on Ms Callinan and Ms Shields.
After fleeing the Doyles' home, leaving his battered girlfriend, Sarah Jane, the Doyles' four orphaned children and both his and Sarah Jane's infant children, Nash wrote letters to his mother and Sarah Jane.
The letters contained admissions of the Doyle and Grangegorman killings, and sought forgiveness. He was arrested two days later.
He subsequently made a very detailed confession about the Doyle murders to police in Galway, in the presence of a solicitor. He then made a further detailed statement about murdering Ms Callinan and Ms Shields at Grangegorman.
This precipitated something of a crisis for the gardai in Dublin. A report of the second admission appeared in The Irish Times on August 27th, 12 days after the Roscommon murders.
An internal investigation was set up under Assistant Commissioner Jim McHugh, the head of the gardai in Dublin, which concluded that Mr Lyons was innocent. He was released after spending nine months in prison.
The alleged confession by Mr Lyons was riddled with inaccuracies. Nash's statement, by contrast, contained detail that only the murderer could know. No move has been made, to date, to charge Nash with the Grangegorman murders.