Thousands of migrants make the dangerous journey each year, enduring brutal conditions and violent treatment as they search for work. There have been several fatal instances of smugglers cramming people into airless trucks, including one left by the side of a highway in Austria in 2015, with 71 people dead inside.

The authorities in Greece found 41 migrants on Monday in the back of a refrigerated truck after a random inspection on a highway in the north of the country, the police said, adding that none of the people were seriously harmed.

Two drivers have been charged in the case of the bodies discovered in Essex. Maurice Robinson, 25, of Northern Ireland, who was believed to be the driver of the truck that picked up the trailer with the victims inside shortly before the bodies were found, was charged on Oct. 26 with 39 counts of manslaughter and conspiracy to traffic people.

The other truck driver, Eamon Harrison, 23, also of Northern Ireland, was charged in Ireland on Friday with 39 counts of manslaughter, human trafficking and immigration offenses. The police said that he had delivered the trailer to a Belgian port before it was put on a ferry to England.