The policemen worked double shifts, putting in four hours of day duty before or after the eight-hour night shift. Then the workload started to take its toll in the bitter weather. Older men went down first, with chills and chest colds. Then some of the less robust younger men started to succumb. Two cases of frostbite were reported from the C-district, where the freezing east wind whipped across the streets from the bay. The depot hospital at Kevin Street quickly filled with the sick and the exhausted.

There were some gains. Larcenies and housebreaking were reduced with the extra policing presence on the streets. Criminals stayed at home at night or drank in the public houses, unwilling to risk being grabbed none-too-gently out of the darkness by ill-tempered DMP men, only too glad to have an excuse to return with a prisoner to the warmth of their station.

Teams of G-men and buckshees interviewed all of Ellen Byrne’s known associates and clients. None of the working girls on Gloucester Street had seen anyone who might match the description given by Constable 35C of a tall man, much less one who looked like a policeman. None of her regular clients could be placed anywhere near her address on the night she died.

Pat Cummins, the C-Division constable who had encountered the man fleeing from the scene of Ellen Byrne’s murder, had been admitted to the hospital at the Kevin Street depot on Lafeyre’s recommendation. Swallow and Mossop went to interview him in his hospital bed.

‘So you think the man you saw was a policeman?’ Swallow said. ‘But you didn’t recognise him.’

Cummins’s face twisted in anguish.

‘I know I’ve seen him before. I just can’t say where or when. Just for some reason I thought to myself, he’s a “polisman.” But don’t ask me for a name.’

‘Describe him, then,’ Mossop prompted him.

‘He was big, athletic. Maybe thirty, maybe thirty-five years. Very agile.’

‘Clean-shaven?’ Swallow asked. ‘Or bearded?’

‘Hard to say in the darkness. It was more an impression.’

‘Fair enough,’ Swallow said doubtfully. ‘Look, when you’re rested and feeling better we’ll ask you to visit the various divisions around the city. It might be that you’ll spot your man.’

Swallow and Mossop were present for Ellen Byrne’s funeral Mass on the Tuesday at St Mary’s Pro-Cathedral on Marlborough Street. It was well attended by working girls from the brothels around Montgomery Street and Gloucester Street, perhaps a score in all. There was no sign of any family. The other girls told detectives that her parents were dead, but that she sometimes spoke about a sister who lived in Wicklow.