Shane O’Brien allegedly killed Josh Hanson, 21, in an unprovoked knife attack at the RE Bar in Hillingdon, west London, on 11 October 2015.
The Metropolitan Police said O’Brien was flown out of the UK on a privately chartered plane from London Biggin Hill Airport and has been travelling “extensively” since.
The 30-year-old, who slipped through the net after he was arrested in the Czech Republic in February 2017, has now been placed on the Interpol’s most wanted list.
He was arrested in Prague for criminal damage and assault under the Italian alias Enzo Mellonceli and released on bail.
Police revealed the near-miss during a fresh appeal to find O’Brien in October last year, with a £50,000 reward for information leading to his arrest and prosecution.
There were reported sightings of the suspect in Gibraltar, as well as in the French city of Nice, following the appeal on the second anniversary of Mr Hanson’s death.
It is believed he may have spent time hiding in the Netherlands and Dubai before his arrest in the Czech capital.
Photos taken of O’Brien when he was detained showed him with long hair, a full beard and a new tattoo of an owl holding a skull, which covers up his previous identifying “Shannon 15-04-16” tattoo.
Mr Hanson’s mother Tracey and his sister Brooke said in a statement on Friday: “Our lives will never be the same without Josh and I would not wish our living nightmare on anyone, it is a pain that no words alone can describe.
“Someone somewhere also knows where O’Brien is and can change the pain and uncertainty that each day brings for us.
“We ask you to try and imagine the emptiness that we have been left to live with, please, please, please do the right thing and make that call or encourage someone else to.”
Detective Chief Inspector Noel McHugh said: “Based on what we know about O’Brien’s lifestyle and interests, we are looking to people in nightclubs and boxing gyms as well as expats and any women he may have become involved with to come forward.
“Please do not assume that someone else will call in, what you perceive to be a small piece of information could in fact be the missing piece of the jigsaw that gets justice for Josh.”
More from UK
95-year-old man arrested on suspicion of murder over death of carer
Boy, 15, arrested after second fatal stabbing in Sheffield this week
Jeremy Corbyn puts Labour on ‘permanent notice’ for snap general election
Man guilty of hammer attack on 96-year-old D-Day veteran Jim Booth
Meghan’s tribute to California in coat of arms design
Man shot ‘in taxi’ by police in Bishop Auckland, County Durham
O’Brien, originally from Ladbroke Grove in west London, is described as white, 6ft tall, with grey eyes and dark brown hair.
Police say he is dangerous and should not be approached. Anyone with information should call 999, the incident room on 0208 785 8099, or Crimestoppers anonymously on 0800 555 111.