A one-legged drug kingpin is wanted after being convicted in his absence over the attempted importation of £8 million worth of amphetamines into the UK.
Richard Wakeling fled to Belfast in January before the start of a 12-week trial which saw him found guilty of drug offences alongside three other men, the National Crime Agency (NCA) said.
The 51-year-old, from Essex, was sentenced on Monday in his absence at Chelmsford Crown Court to 11 years in jail for conspiring to import drugs, the NCA added.
The discovery by Border Force of plastic drums carrying liquefied amphetamine in April 2016 sparked the NCA investigation.
Lorry driver Lesley Muffett had attempted to board a train through the Channel Tunnel as he transported furniture from Italy, the organisation said.
He stopped at Ternat in Belgium and phone evidence showed he was directed by fellow lorry driver Stuart Davidson to collect the drugs, the NCA said.
Wakeling, who was in contact with drug suppliers in Belgium and the Netherlands, liaised with Davidson and fellow gang member Darren Keane to arrange the journey, the organisation added.
NCA senior investigating officer Paul Green said: "These men were involved in a serious conspiracy to import a large quantity of dangerous drugs.
"We know they had links into other organised crime gangs in Europe and it is almost certain that this wasn't the first time they had done it."
The NCA, which said Wakeling, of Wharf Road in Brentwood, has family links to Thailand, appealed for information on his whereabouts.
"We strongly suspect that Wakeling fled abroad, possibly to Thailand were he has strong family links.
"But it is likely there are people here in the UK who hold clues about his movements after he arrived in Belfast on 6 January, and I'd appeal for anyone with information to come forward.
"He has a prosthetic leg and needs regular medical treatment.
"The NCA has an international reach and he should know distance isn't a barrier to us finding him. We are determined he will be returned to the UK to serve his sentence.
"Until we find him, he'll spend every day looking over his shoulder."
Keane, 34, of Kiln Drive, Milton Keynes, was jailed for nine years, Davidson, 65 of Chesham Drive, Basildon, Essex, was handed an eight-year sentence, while Muffett, 59, of Campbell Road, Witham, Essex was given six years in prison.