Henry Barry, 4th Baron Barry of Santry

Although Lord Santry was not immediately apprehended, there is no reason to think that the Crown intended that he should escape justice; indeed the authorities clearly aimed not only to prosecute him but to secure a conviction. Even in an age when the aristocracy enjoyed special privileges, the murder of Murphy, who by all accounts was an honest and hardworking man with a wife and young family to support, had shocked public opinion, whereas Lord Santry was regarded, even among members of his own class, as a public nuisance. In due course Santry was arrested and indicted for murder. He demanded, as the privilege of peerage, a trial by his peers. The trial, which took place in the Irish Houses of Parliament on 27 April 1739, aroused immense public interest.[7]

Lord Wyndham, the Lord Chancellor of Ireland, presided in his office Lord High Steward of Ireland, with 23 peers sitting as judges. The Attorney-General for Ireland, Robert Jocelyn, and the Solicitor-General for Ireland, John Bowes, led for the prosecution.

Bowes dominated the proceedings and his speeches made his reputation as an orator. Thomas Rundle, Bishop of Derry, who as a spiritual peer was only an observer at the trial,[8] said "I never heard, never read, so perfect a piece of eloquence...the strength and light of his reason, the fairness and candour".[9] The Bishop was scathing about counsel for the defence, describing the performance of Santry's counsel as "detestable".[10] The defence case was that Murphy had died not from his wound but from a long-standing illness, but in view of the medical evidence produced by the prosecution this was a hopeless argument. According to Bishop Rundle, Santry's counsel failed even to mention the possibility that Murphy, who lingered for 6 weeks after being stabbed, might have died through inadequate medical care. Given the overwhelming evidence of Lord Santry's guilt, however, any defence would probably have been useless, and despite what was described as their "looks of horror", his peers had little difficulty in finding Santry guilty. Wyndham, who had conducted the trial with exemplary fairness, pronounced the death sentence.[11]

King George II, like all British monarchs, had the prerogative of mercy, and a campaign was launched by Santry's friends and relatives to persuade the King to grant a pardon. Their plea seems to have concentrated on the victim's low social standing, the implication being that the life of a peer was worth more than that of a tavern worker, despite the victim's blameless character and the savage and wanton nature of the murder. The King proved reluctant to grant a pardon,[12] and for a time it seemed that Santry must die, but in due course a reprieve was issued. Popular legend had it that his uncle Sir Compton Domvile, through whose estate at Templeogue the River Dodder flowed, secured a royal pardon for his nephew by threatening to divert the course of the river, thus depriving the citizens of Dublin of their main supply of drinking water.[13]

River Dodder today

On 17 June 1740, Lord Santry received a full royal pardon and the restoration of his title and estates; soon afterwards he left Ireland for good and settled in England. His last years are said to have been wretched: although he made a second marriage shortly before his death, he was abandoned by all his former friends, was in great pain from gout and prone to depression.[14] On his death in 1751 the title became extinct; his estates passed to his Domvile cousins. His widow Elizabeth outlived him by many years, dying in December 1816.