A £10,000 reward is being offered to find a man accused of stabbing a Deliveroo driver to death in north London earlier this year.
Takieddine Boudhane was attacked on his moped during a suspected road rage clash with Nathan Smith, police said.
Murder detectives believe Mr Smith stabbed Mr Boudhane, before fleeing the country hours later.
Det Ch Insp Neil John said the 27-year-old was last known to be in Zurich, Switzerland, days after the stabbing.
A European Arrest Warrant has been issued for Mr Smith who is believed to have links to the Camden, Islington and Kentish Town areas of north London.
Mr Boudhane, an Algerian national, had been living in the UK for about three years and worked as a takeaway delivery driver for Deliveroo and Uber Eats.
The 30-year-old was stabbed on Charteris Road in Finsbury Park on 3 January. His death sparked the first murder investigation in London this year.
Det Ch Insp John said Mr Smith has a tattoo on his right forearm that says "count your blessings".
He told the BBC: "We know he left the UK on 4 January to go to [Salzburg] Austria and we have had reliable information to know he was in Switzerland on 5 January.
"From that point on we don't know where he is, hence the appeal to the public.
"We are confident he has now moved elsewhere in Europe or potentially further afield."
Det Ch Insp John added: "I would appeal to Nathan Smith himself - make no mistake, this will not go away.
"You should do the decent thing for Mr Boudhane's family and your own family and surrender yourself as soon as possible."