LONDON U.K. police have charged a truck driver with 39 counts of manslaughter and conspiracy to traffic people in the 39 people found dead in a truck container in southeastern England.

Authorities announced the charges Saturday against Maurice Robinson, 25, of Northern Ireland, who was arrested shortly after the grisly discovery of the bodies was made in southeastern England early Wednesday. He is due to appear in court Monday.

In addition to manslaughter and trafficking, he also faces charges for conspiracy to assist illegal immigration and money laundering.

Three other people have also been arrested on suspicion of human trafficking in the case, British police said Friday. A 38-year-old man and 38-year-old woman from Warrington and a 48-year-old man from Northern Ireland who were arrested on suspicion of conspiracy to traffic people and manslaughter remain in custody.

U.K. authorities have been conducting a sprawling investigation into how the bodies came to be in a truck container southeastern England in what is one of the country’s worst human-smuggling cases.