A 23-year-old man been charged in connection with the deaths of 39 people in a lorry trailer in Essex.
Eamon Harrison appeared in court in Dublin after being detained on a European Arrest Warrant and extradition proceedings have been launched.
It comes as Essex police made a direct appeal to two other suspects.
Officers said they had spoken to one of the men, Ronan Hughes, 40, by phone. He is wanted along with his brother, 34-year-old Christopher Hughes, on suspicion of manslaughter and human trafficking.
From Armagh in Northern Ireland, they also have links to the Republic of Ireland, and to the road haulage and shipping industries.
"Today I want to make a direct appeal – Ronan and Christopher, hand yourselves in to the Police Service of Northern Ireland (PSNI)," said Detective Chief Inspector Daniel Stoten.
"We need you both to come forward and assist this investigation."
More from Essex Lorry Deaths
Mr Stoten added: "Although we have already spoken to Ronan Hughes recently by telephone we need to have a conversation with him and his brother in person.
"Talking to Ronan and Christopher is crucial to our investigation and the sooner we can make this happen the sooner we can progress and continue with our investigation."
Mr Stoten said a lorry believed to be connected to the brothers was stopped and seized by the PSNI on Thursday, but no further arrests were made.
He said the Essex force would continue to work with the PSNI and Irish police "until Ronan and Christopher Hughes have come forward or are arrested".
The bodies of eight women and 31 men were found in a refrigerated trailer at Waterglade Industrial Park in Grays, Essex, in the early hours of 23 October.