A lorry driver has been charged with the manslaughter of 39 people found dead inside a refrigerated trailer.
Maurice Robinson, 25, was arrested after the bodies of 31 men and eight women were found in Grays on Wednesday.
He is further charged with people trafficking, immigration and money laundering offences, Essex Police said.
Mr Robinson, of Laurel Drive, Craigavon, Northern Ireland, is due before Chelmsford Magistrates' Court on Monday.
Three others, a man and a woman, both 38, from Warrington, Cheshire, and a 48-year-old man from Northern Ireland remain in police custody.
All three were arrested on suspicion of manslaughter and conspiracy to traffic people.
A man in his 20s arrested by Irish police in Dublin was said to be "of interest" to the Essex Police investigation.
Earlier police said efforts to identify the 39 people were focusing on the Vietnamese community.