On the morning of 7 March 1997, the bodies of two elderly female patients were discovered in their sheltered accommodation at Grangegorman Psychiatric Hospital in Dublin.

It would be a further 16 years before Mark Nash was convicted of the notorious Grangegorman murders, but not before Dean Lyons, an innocent man, spent months in prison for a crime he did not commit, only to tragically die of a heroin overdose before his name was cleared.

Here Alan Bailey, a retired member of the Garda Siochana who worked on the original case and who always insisted Lyons was innocent, recalls the investigation of the most brutal murders in Irish criminal history, and how pressure on the Garda Siochana to solve the crime led to one of the greatest miscarriages of justice in the history of the Irish state.