Police have released an image of the man they believe killed journalist Lyra McKee.
The Police Service of Northern Ireland have now launched a public appeal for anyone with information about the suspect to come forward.
Three men are pictured in the CCTV footage, but police believe the "stocky" figure is the gunman who killed 29-year-old Ms McKee, after firing into a crowd of people.
The trio - one said to have been carrying a crate of petrol bombs - were seen walking across Central Drive in Creggan area a minute before the killing.
PSNI detective superintendent Jason Murphy, said: "I think people in the community know who they are and I'm asking them today to come forward to help us.
"I'm releasing footage today from the night of Lyra's murder and I want to appeal to anyone who recognises or knows these people to talk to us."
Mr Murphy also made a direct appeal to the gunman, asking him to come forward and explain why he fired the shots and explain to Ms McKee's family why she died.