The Garda chief leading the investigation into the murder on Halloween of 21-year-old Lorcan O’Reilly has said there are people who “know what happened” and he urged them to come forward.

Separate knife attacks over Halloween night in Dublin left one man dead and another two fighting for their lives.

In the piercing morning sun, as massgoers gathered at nearby John’s Lane Church, forensic officers combed the courtyard at Oliver Bond flats in The Liberties, Dublin, for clues surrounding the fatal stabbing of a young man just hours earlier.