The Dublin Metropolitan Police Detective Department began keeping reports about the movements and associations of pro-independence suspects in June 1915, nearly a year before the Easter Rising.
Now the Irish National Archives has digitized those reports, which are being uploaded to its website on a weekly basis through April 2016. INA says:
The reports detail intelligence gathered at a number of key city centre locations, including the shop of Thomas J Clarke at 75 Parnell Street, the Irish Volunteers Office at 2 Dawson Street, the Irish National Forester’s Hall at 41 Parnell Square, and the headquarters of the Gaelic League at 25 Parnell Square. … Major events which took place in 1915 and 1916 are recorded in the reports, including the funeral of the Fenian leader Jeremiah O’Donovan Rossa (1 August 1915) and the Annual Convention of Irish Volunteers (31 October 1915).
The Irish Times noted, “Despite all the surveillance by the Dublin Metropolitan Police, the Rising, when it happened, was regarded as a massive failure of intelligence. As a result the long-serving chief secretary to Ireland Augustine Burrell resigned in the weeks after the Rising having been blamed for not foreseeing the rebellion.”
Access the records here. Warning, using the search function captures some words but not others. It’s best to read the files if you don’t want to miss anything. You might find the name of someone in your family’s past.