Nico Ramsay, 19, was found with a stab wound to the chest in Napier Avenue, Southend, on Saturday 13 February. He died in hospital four days later.
Essex Police said officers are looking for Allcie Houlder, 21, in connection with the death.
He was last known to be living in Mantle Way, Stratford.
Mr Houlder has links to Southend, Romford and Newham.
He is described as 5ft 11in (1.8m) tall, with dark skin, and has a small scar on his chin and the word Tarnia tattooed on the right side of his neck.
Mr Houlder is believed to have left the UK and taken a ferry from Dover to France on 19 February.
Mr Ramsay's family issued a statement paying tribute to him.
"Nico was a lovely, good-natured, charismatic and humorous young man who had only just turned 19," they said.
"He had a life full of hope and promise ahead of him."
Murder inquiry detectives have named a man they want to speak to in connection with the death of a teenager who was stabbed in Essex.