I don’t know what led Michael Feather to emphasize the private-school aspect of the case from its inception. Perhaps his own experiences as a Clongowes boy told him something about our world. In any case, he knew from early on that Conor’s death had not been the result of a mugging, because Conor’s wallet was still in the pocket of his jeans when he arrived in the emergency room.

Eileen and Brendan Harris were intractable in their mistrust of Michael Feather. This began, I think, in the hospital, when Brendan asked for Conor’s effects and the garda gently explained that these would have to be kept as evidence. Eileen Harris would blame Michael Feather’s incompetence for the eventual overturning of Richard Culhane’s manslaughter trial. But by this time Eileen was blaming everyone, because she could find no obvious target for her anger.

In fact Michael Feather was thorough and methodical. He was a moustachioed man with a large, block-shaped head, who suffered from a stammer that afflicted him only on words that began with the letter H. It took the form of a peculiarly toneless repetition of the initial syllable. ‘I’ll ha-ha-have to speak to you about this at the ha-ha-house,’ he would say in his rustic monotone.

‘He’s doing it on purpose,’ Eileen Harris would complain. And indeed, the stammer seemed deliberate; it lacked the embattled quality of a true impediment.

I trusted Michael Feather. In his press conferences he was circumspect, even boring. He gave very little away. And he did find out who killed Conor Harris, even if it took him almost a month.

Eventually the guards contacted the principals of the southside private girls’ schools and asked them to take the names of any students who had been in Harry’s on 31 August. This produced a slightly longer version of Joanna Carruthers’s list. So Michael Feather’s team began the business of calling on all of these girls in their houses in Stillorgan and Killiney and Dalkey and Ranelagh and Milltown and Mount Merrion and Shankill and Blackrock and Donnybrook and asking them what they’d seen.

All over south County Dublin girls were surprised on September evenings at their homework by uniformed guards with notebooks and questions. Most of them enjoyed the drama, I think. For a couple of days at St Anne’s it became a point of pride to have been visited by the gardaí. Girls who hadn’t yet been interviewed prayed for the opportunity to air their own particular theory about Conor’s death. Most of what the guards uncovered consisted of improbable speculation. Several girls – I knew them, vaguely – had decided that the source of the argument (and everyone was sure there had been an argument, even the people who had seen nothing, who had been too drunk to pay attention) was a girl – specifically, Laura Haines, whom every one of these private-school girls knew or had heard about.

There was a problem of age. Most of the girls who were interviewed at this point in the investigation were three or four or five years younger that Conor Harris and his peers. So they had only the most tenuous of links to what had actually happened in Blackrock that night. It took the guards some time before they could identify the people who knew Conor directly.