CCTV of the main suspect in Lyra McKee's murder has been released by police.
Officers shared fresh footage from the day the journalist was shot dead and appealed for people to come forward.
The video shows a number of men. The main suspect is shorter than the other two in the footage and of stocky build.
PSNI Detective Superintendent Jason Murphy said: "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."
Three men, one of whom is said to have been carrying a crate of petrol bombs, were seen walking across Central Drive a minute before the killing.
Speaking about the main suspect, Mr Murphy said: "He is shorter than both of the other men and is of stocky build. It is of my belief that he is the gunman that fired indiscriminately into the crowd and placed the community and police officers at risk.
"I believe he is the person who took the life of Lyra McKee.
Appealing for assistance in the search, he said: "People saw this young man and his associates.
"I think people in the community know who they are and I'm asking them today to come forward to help us."
He called on further public support in the search for the killer, stating more than 140 people had provided information so far, and 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.
Ms McKee, 29, was shot dead while observing rioting in Londonderry last Thursday.
Hundreds of mourners attended her funeral on Wednesday in Belfast.
The New IRA, an amalgam of armed groups opposed to the peace process, said it was behind the killing.
It apologised for her death saying it was a "tragedy" and that it happened because she was standing near "the enemy", seemingly in reference to police.
It recently claimed responsibility for parcel bombs sent to London and Glasgow in March.