The murder of two former IRA veterans within three months of each other caused a political falling-out that threatened the stability of Northern Ireland and almost brought an end to the power-sharing Executive.
When Kevin McGuigan plotted to kill his one-time friend turned sworn enemy Gerard 'Jock' Davison, he believed there would be no retaliation.
Davison, a former IRA commander, had been expelled from the organisation.
Despite this, he still commanded the respect of the rank and file of the republican movement, those who had not transitioned into politics but were still, at least until that point, publicly supportive of the peace process.
On the day of his murder, as his body lay in the street of the Market area of South Belfast where he had lived and worked, covered in a police forensic tent, men started to gather at the scene.
A few members of Sinn Fein arrived, as did noticeable and known IRA members. Discussions about how to avenge their fallen 'comrade' were already under way.
An 'internal investigation' established how McGuigan had obtained the murder weapon, a brand new Makarov automatic handgun, a type of weapon previously used only by Dublin drug gangs.
The 'investigation' by those loyal to Davison quickly established who helped in the planning of the murder and who took the gun, which has never been recovered, away from the scene.
From that moment, Kevin McGuigan, once a feared republican hitman, was living on borrowed time.
His murder came just three months later. The fallout was instant. The PSNI said it believed Provisional IRA members had carried out the murder.
That was rejected by Sinn Fein, which said the IRA "had left the stage".
Then DUP leader Peter Robinson said the party should be excluded from the Executive and called on the Secretary of State to take action.
Mr Robinson also stepped aside as First Minister and pulled ministers out of the devolved government.
They returned to their posts after then Secretary of State Theresa Villiers released the findings of an official assessment of paramilitary activity.
It also led to the formation of the Independent Reporting Commission, created under the terms of Fresh Start Agreement, to monitor progress on tackling paramilitary activity.
While the political fallout from the murder seemed to settle, the damage to relations in the small communities of the Market and Short Strand were much more difficult to repair.
It also caused significant internal problems in the mainstream republican movement.
While it was known for wielding iron glove-like discipline, the episode had seen senior people break ranks to make a point to anyone who would consider seeking retaliation for past activity.
The inquests into both men's deaths were a hornet's nest of complicated relationships and murderous pasts, along with the ongoing surveillance by the security services of former IRA members and what was and was not known prior to the killings.
It is a period that is far from over. The bad feeling still flows and could cause yet more bloodshed on the streets of Northern Ireland.