Police are searching for a man they want to talk to in connection with a murder in east London.
Jason Junior Romeo, 20, was fatally stabbed outside an address on Bodney Road in Hackney following an altercation at about 6pm on Tuesday, police said.
Officers have released an image of Renaldo Roberts, 25, who they would like to speak to in connection with the inquiries.
Mr Roberts has links with Hackney and Dagenham, the Metropolitan Police said, but it warned members of the public not to approach him and instead call 999.
Three men have been charged with murder and appeared at Thames Magistrates' Court on Monday.
They are Raynolph Asante, 22, of Pembury Road, Travis Mitchell, 21, of Bodney Road, and Rhamyah Bailey-Edwards, 21, of Williams Avenue in Walthamstow.
Scotland Yard said an 18-year-old man was arrested on suspicion of murder on Sunday and remains in custody.
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Detective Superintendent Kelly Allen, from Specialist Crime North, said: "This investigation has moved quickly with officers arresting four men within five days.
"We are now in the position to release Renaldo Robert's details, who we would like to speak with to assist with our inquiries."
Detective Superintendent Vicky Tunstall of Central East Command Unit said: "We understand that the increased police presence in Hackney this week will be concerning for residents.
"Our officers will remain in the area carrying out increased patrols.
"I'd encourage residents to discuss any concerns they may have with officers on patrol.
"Reducing knife crime is a key focus and we will continue to work closely with partners for a safe borough.
"I'd encourage anyone with information about those who could cause harm within our community, to contact us directly or through Crimestoppers."
Anyone with information on Mr Roberts' location is asked to call 999 as soon as possible quoting 5635/18Feb.
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