Lincolnshire Police detectives are appealing for information to locate 19-year-old Eimantis Gochman, who is wanted in connection with the death of Sam Davies.
Sam, 23, died after sustaining serious knife wounds in an incident at Coleridge Gardens, Lincoln, on Thursday evening.
Three men – aged 18, 23 and 24 – have been arrested on suspicion of murder. They remain in police custody.
Detective Chief Inspector Richard Myszczyszyn, from East Midlands Special Operations Unit, is leading the investigation.
He said: “This is a fast-moving investigation and we are very keen to speak to Eimantis Gochman.
“Anyone with information about his whereabouts should contact us immediately. Even the smallest detail could be crucial.
“If you see him, please do not approach him but get in touch with Lincolnshire Police.”
Anyone with information or sightings of Eimantis Gochman should call 999 quoting Incident 536 of May 27, or submit information through the dedicated portal. Information via this portal can be entered anonymously.