The 34-year-old man, from Limavady, was arrested on Tuesday in Banbridge over death of a man and facilitating illegal entry.
Currently, the suspect is in police custody in Northern Ireland, however he is set to be probed by Essex Police after his return to England.
Acting Detective Chief Inspector Martin Pasmore, of Essex Police has said: “This is a fast-moving investigation which has already involved a number of police forces and law enforcement agencies from across the United Kingdom and Europe.
The victim, Meet Singh Kapoor, 40, from Kabul was found dead after failing to survive in an air-tight container on a UK-bound ferry in Essex which carried 35 Afghan Sikhs as illegal migrants.
A post mortem examination that took place on Sunday was unable to establish the cause of death.
Being viewed as one of the shocking case of people trafficking in recent British history, the 35 people were discovered after dock workers heard banging and screaming coming from one of the containers. The 34 survivors include 10 men, nine women and 15 children, with their ages ranging from one to 72.
All the survivors were suffering from dehydration and hypothermia.
Essex Police Superintendent Trevor Roe has told the group, believed to be from Afghanistan and predominantly of the Sikh faith, have finished speaking to police and are now being cared for by Home Office officials.
Police officials are now trying to discover the route they took to Britain.
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