Eleven years ago, a peace agreement in Northern Ireland ended decades of sectarian violence between Catholics and Protestants. Despite that agreement, there are still many open wounds from the conflict -- justice still not served for thousands of families whose loved ones were murdered or vanished.

Following two attacks by Irish Republican Army splinter groups this week, Northern Ireland is on edge, fearing a return to the "Troubles" -- the three decades of violence that killed more than 3,300 people.