Police have sent letters to residents in Creggan in Londonderry appealing for information about the murder of journalist Lyra McKee.
The 29-year-old was shot dead as she observed rioting in the area and Saturday, 18 April, marks the first anniversary of the killing.
Paul McIntyre, 52, from Kinnego Park in the city has been charged with her murder, which he denies.
Speaking on Good Morning Ulster, Det Supt Jason Murphy, who is leading the investigation, said the letters to the Creggan community are not a standard part of a PSNI investigation, but that this murder case "has been everything other than ordinary".
Comparing the case to a "1,000-piece jigsaw", he said the community response so far had been positive but he needed further public assistance.
Mr Murphy said there are up to 17 suspects in the investigation and the gun used to kill Ms Mckee still had not been found.
"While this appeal for information is being distributed by the police, it is also a direct appeal from the McKee family for help in getting justice for Lyra," he said.
In the letter, Mr Murphy wrote that the charges “do not signify the end of the investigation”, rather “it is only the beginning”.
“Lyra’s murder was not committed in isolation, nor did it involve only one person,” he continued.
“The events that led up to Lyra being shot, and the events afterwards, are equally important."
'I miss my life with her'
In an interview with BBC Radio Foyle, Lyra McKee's partner, Sara Canning, said it had been the "most horrific and surreal year".
"I miss my life with her. If I could go back to this time last year I'd do things differently. I wish we stayed in bed that night and just read books and talked nonsense to each other.
"I really hope we get justice. I don't want to give up hope."
Mr Murphy has asked for the public’s help in gathering mobile phone footage or photographs, first-hand accounts and to identify people involved in the disorder that night.
“For the purposes of this investigation I will offer anonymity to those who wish to talk to us," Mr Murphy said.
“Ease your conscience and help us resolve a small part of the nightmare that the McKee family live through every single day.”