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."

Western Power Distribution (WPD) said that without expensive investment the grid would struggle to cope with taking any more power.
And developers could be asked to pick up "a large proportion of these costs".
Renewables advisor Regen SW warned charges, totalling up to £4m, may be a barrier to renewable energy schemes.
New renewable energy projects in the South West rose from 936 in 2009/10 to 47,423 in 2011/12, said Regen SW.
Since 2009, Cornwall Council has approved nearly 50 solar farms covering more than 1,600 acres.
WPD said all the solar farms in the pipeline would produce another 250 megawatts (MW) of power and parts of its system "would be at the limit of the generation they can accommodate".
It pinpointed the Pyworthy and St Tudy areas as being closest to capacity.
WPD said in a statement: "We have seen many large scale photovoltaic (PV) generation applications, as well as a few wind farms across the South West and particularly in Cornwall over the last few years.
"To connect further would therefore require extensive reinforcement of existing or building of new circuits, which can be quite expensive."
It said costs could be £1m to £4m depending on the size of the changes.
Merlin Hyman of Regen SW, which promotes renewable energy in the region, said: "It is not a secret that the grid's capacity is the biggest constraining factor for the growth of solar energy.
"We are working hard with Western Power Distribution to ensure there is investment in reinforcing networks, otherwise the grid will be a major barrier to some renewable energy projects.
"Investment to create robust local networks will enable more local generation of secure energy rather than relying on uncertain imported fossil fuels."
He said Regen wanted WPD to increase its plans to spend £3m a year reinforcing the network which "we don't think is enough".
The Energy Networks Association said: "Large scale generation projects will benefit from the energy they will sell to consumers and so it is fair that they cover the cost to reinforce the network that their project will profit from."
Climate Change Minister Greg Barker said there was a growing need in the county to "manage additions to the grid more carefully".
"Cornwall is the most extraordinary powerhouse for natural energy and it's very exciting," he said.
"But we need 21st century connections to get that energy out of Cornwall and into the rest of the country."

The culprits tried to to pull the cashpoint at Aboyne Filling Station free using a blue Land Rover Defender at about 01:45 on Sunday.
The vehicle was abandoned at the crime scene.
Det Insp Richard Taylor appealed for anyone who saw the vehicle in the area in the hours before the incident to contact Police Scotland.
It is not known how much money was in the machine.
The Land Rover Defender is thought to have been stolen from the Dinnet area.
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.
[NEXT_CONCEPT]
Renewable energy projects are putting parts of Cornwall's electricity grid under severe strain, according to the region's power firm.
[NEXT_CONCEPT]
Thieves fled empty-handed after an attempted raid on a cash machine in Aberdeenshire failed.