The horror of Bloody Sunday and the decades of injustice which followed cast a long shadow over the city.
That shadow was lifted, to an extent, with the findings of the Saville Inquiry into the massacre and the subsequent apology from David Cameron - an unprecedented move by a British prime minister.
While these addressed some of the moral responsibilities of the British government, the legal responsibilities remained.
The murder investigation launched by the PSNI was a major step in that process and yesterday’s call for witnesses to come forward was another important milestone on the journey.
The detective leading the investigation acknowledged that it would be lengthy and complicated but no doubt the people of Derry will answer that call in support of the families of those killed and wounded, just as they did through the decades of their long and dignified campaign for truth and justice.