The Garda Ombudsman has launched an investigation into the murder of Garda Anthony Golden.
He was shot in Omeath, County Louth in October 2015 by Crevan Mackin - who then took his own life.
Mackin's partner Siobhán Phillips suffered life changing injuries during the incident.
The Taoiseach is being urged to recall the Dáil after new information emerged in a Prime Time Investigates program which alleges Gardaí had a litany of information about Mackin and the weapons and bombs he had.
Sinn Féin Deputy Leader Mary Lou McDonald says its disturbing.