Eamonn Harrison, 22, appeared in Dublin High Court yesterday after he was arrested on a European Arrest Warrant. He is charged with 39 counts of manslaughter, along with human trafficking and immigration offences, Essex Police said.
The force said extradition proceedings have been started to bring Harrison, from Newry in Co Down, Northern Ireland, to the UK.
He was remanded in custody in Dublin’s Cloverhill Prison until 11 November.
Extradition proceedings came as Essex Police said the migrants found dead were all believed to be Vietnamese nationals.
Assistant Chief Constable Tim Smith said: “We are in direct contact with a number of families in Vietnam and the UK, and we believe we have identified families for some of the victims whose journey ended in tragedy on our shores.”
Local media reported police in Vietnam’s Ha Tinh province had arrested two people in connection with the deaths after launching an investigation into suspected human trafficking. It is understood wanted suspect Ronan Hughes, 40, has twice spoken to police by telephone.
Detectives have urged him and his brother Christopher, 34, who are both from Armagh in Northern Ireland, to hand themselves in.
The pair are wanted on suspicion of manslaughter and human trafficking after the bodies of eight women and 31 men were found in a refrigerated trailer attached to a lorry in an industrial park in Grays in the early hours of 23 October. Ronan Hughes is understood to have identified himself to a custody officer after calling Essex Police shortly after lorry driver Mo Robinson, 25, was arrested following the discovery.
A Police Service of Northern Ireland (PSNI) detective later called Hughes and had a conversation with him.
Essex Police Detective Chief Inspector Daniel Stoten said: “Today I want to make a direct appeal – Ronan and Christopher, hand yourselves in to the PSNI. We need you both to come forward and assist this investigation.
“Although we have already spoken to Ronan Hughes recently by telephone, we need to have a conversation with him and his brother in person.” The detective 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.