Senior detectives investigating the murder of journalist Lyra McKee have issued a fresh appeal ahead of the first anniversary this weekend.
Letters have been sent from the PSNI's Major Incident Team to people living in the Creggan in Londonderry directly appealing to them to think back to the tragic events of a year ago.
Ms McKee (29) was shot dead by a dissident republican gunman during street disorder in Derry last April.
A man has since been charged in court with Ms McKee's murder and a number of other offences. He denies all charges.
Detective Superintendent Jason Murphy, who is leading the investigation, said their plea for information into the connection of the killing was about getting justice for the late writer's loved ones.
"(Tomorrow), 12 months will have passed since journalist Lyra McKee was shot dead during rioting at Fanad Drive in Creggan," he said.
"Sadly, Lyra's mum died very recently without seeing justice for her daughter. 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.
"The community as a whole was devastated by Lyra's murder. Condemnation of her killing was unequivocal. That condemnation brought support for the community's response from countries across the world."
In his letter sent to Creggan residents, he says: "Since Lyra was killed, many of you may have spoken with my team of detectives.
"We have strived to conduct the investigation with sensitivity and care. My investigation is being carried out with the community and this has enabled us to gather important evidence which has resulted in one man being charged with Lyra's murder and a second man being charged with offences connected to the rioting which preceded it.
"My sincere thanks go to all those who have helped to date.
"However, these charges do not signify the end of the investigation. For the police service, me and my team of detectives, it is only the beginning.
"A huge amount of work has been done and massive amounts of community help has enabled us to piece together the events of 18 April 2019 and gain a clear understanding of the roles played by those who were involved."
Mr Murphy adds: "Lyra's murder was not committed in isolation, nor did it involve only one person.
"The events that led up to Lyra being shot, and the events afterwards, are equally important. I am asking the community to reach into its conscience and tell us what it knows.
"Lyra's family cannot begin the grieving process without the information about Lyra's murder that they deserve.
"One year on, I am still seeking the evidence to bring every single person who was involved that night to justice. I cannot deliver that without you."
He goes on to state that investigating officers are specifically interested in gathering mobile phone footage or photographs from anyone who was present at the scene of the killing, as well as speaking to anyone who attended the riot and can identify those involved in the disorder.
Mr Murphy said he is also interested in anyone who can provide first-hand evidence relating to the events which preceded or followed Lyra's murder.
"We have made the public portal available again, so that you can contact us discreetly. Log onto https://mipp.police.uk from your mobile, tablet, laptop or other device," he revealed.
"We do not need to keep your mobile phone or device, we are only interested in downloading the videos or images of that night. Please tell us what you know. If you want to speak to me directly, let me know via the MIPP application, email me at firstname.lastname@example.org or ring me via 101."