The usual enquiries were made into the McDonnells as the search began for possible enemies, motives and reasons for any antipathy in the area towards the family from Ballygar, Roscommon. The slaughtered were all middle-aged, and had lived in Malahide for six years. They were well-liked and there were no known enemies or feuds that might have been linked to that horrendous attack and mass murder. The servant who was killed first was destined to be a part of the slaughter – he had just returned from holiday and came home very late – apparently just a little time before the arsonist and killer.

It took only ten days to find a suspect and, as usual in such cases, the person who reported the deed was the main suspect. There was a coroner’s court led by Thomas Early, and that had to be adjourned until post-mortems could be done. Before the suspect was arrested, there had been some days of frustration for the police, as only after the pathology was complete was there any fragment of a chance that there might be a lead. But then a fuller story emerged and the arrest of Henry McCabe was announced. He was detained in the Malahide Police Station. The series of events was then put together, starting with a call at the house by a rate-collector a day before the fire led to the fact that at that time the house had been locked and was silent. McCabe was charged with six counts of murder before the Police Commissioner, Mr McMahon, and he was soon on remand in Mountjoy Prison.

After details had been given on the post-mortem reports by Francis Fogarty and Peter O’Toole of the State Laboratory, McCabe stood in Kilmainham District Court and there it was learned that McCabe had allegedly used arsenic, as that poison had been found in all six bodies.

At the trial at the Central Criminal Court the press and public had six days of reports and statements on this very nasty case; statements had been taken from eighty people and over the trial period there were sixty-three witnesses in court. McCabe’s reign of terror at La Mancha had included brutal physical attacks on his victims and then the administering of arsenic. The court report made the point that ‘all the bodies bore dreadful wounds’. The judge, Mr Justice O’Byrne, said in his summing up that there had been no-one from the family seen by anyone at all except the man in the dock; he stated that McCabe ‘was the only person who had the opportunity to commit the crime’.

The horrible facts were plain and powerful: the use of a can of paraffin and a candlestick had been ascertained, and all three men had died from fractured skulls quite clearly done by the impact of a blunt instrument. What emerged was that McCabe had been so stupid that he had some of his victims’ clothing at his house. He had set out to rob the family, but had been violent from the beginning, hitting Clarke with a spanner from behind as he sat down to milk a cow. After that he had put small quantities of arsenic into the food of the victims remaining alive and forced them to their beds before starting the fires. His other fires were a vain effort to cover up all the murderous activity.

It took the jury fifty minutes to decide on a verdict of guilty, and all McCabe said before sentence was passed was ‘All I have to say is God forgive them. I am the victim of bribery and perjury.’ The death sentence was given, and McCabe had a date with the hangman on 9 December 1926. There was a desperate appeal, and this was heard on 23 November when he had applied for legal aid and a transcript of the trial. His application for appeal was granted but it came to nothing.

Thomas Pierrepoint hanged Henry McCabe, forty-eight-years-old, on 9 December 1926. The death was unremarkable for Pierrepoint, with no obstacles and stresses above the usual. Dubliners were more than happy to see this killer exit the world and leave them feeling a little safer. The callous murderer would never have expected to figure in a major work of literature by one of the great twentieth century Irish writers, but in fact the murderous gardener’s exploits were fictionalised by Samuel Beckett in his book More Pricks Than Kicks eight years after the hanging (1934).