Police are urging a woman who recorded a fight where a filmmaking student was stabbed to death to come forward, saying the video will be “vital evidence”.
Metropolitan Police have called the young woman or teenager a “key witness” who could help officers to “piece together the sequence of events” in Primrose Hill on Tuesday.
Finbar Sullivan, 21, was killed shortly after the fracas.
The woman was captured on film recording the fight. Police said she has not committed any crimes.
In the footage, she was wearing blue denim shorts, black trainers and a pink vest.
Detective inspector Andy Griffin, who is leading the investigation, said police need to speak to her “as soon as possible”.
“My team continues to pursue several urgent lines of enquiry to establish why Fin tragically lost his life,” he said.
“I believe this woman’s account of events, as well as the video she captured, will provide vital evidence.
“To reiterate, she has not committed any offence but we are urging her, or anyone who may know her, to come forward and assist our investigation.”
A second man, believed to be in his 20s, was found nearby in Regent’s Park Road with knife wounds and was taken to hospital.
Police said his injuries are non-life-threatening and non-life-changing.
Mr Sullivan’s father, Christopher Sullivan, earlier told the Daily Mail his son had gone to Primrose Hill to use a new camera he had got for his birthday.
“This is the worst tragedy I could ever imagine,” the 65-year-old told the newspaper on Thursday.
“He’s my only son… I had him when I was 45. He can never be replaced.”
He added: “I’m so broken-hearted, I can’t believe it.
“He was the most beautiful, lovely, outgoing, loving boy. He was just a really lovely person.
“And why he was targeted, we have no idea.”
Mr Sullivan said his son had ambitions to follow in the footsteps of his grandfather, cameraman Michael Seresin, who worked on Harry Potter And The Prisoner Of Azkaban and Rambo III.
“All I can tell you is he was the subject of an indiscriminate stabbing. He was not a gang member,” Mr Sullivan told the Daily Mail.
“He was just a little groovy 21-year-old who loved movies and making films. He didn’t drink, he didn’t smoke, he didn’t go out.
“He’d stay at home editing his films six nights a week.”
Police said no arrests have been made and have asked anyone with information to contact them on 101, quoting reference CAD 6448/07Apr, or Crimestoppers anonymously on 0800 555 111.
