Two more suspects have been arrested following last year’s tragic discovery of dozens of bodies inside a refrigerated truck in southeastern England, British police announced Tuesday, along with preliminary results on how the victims died.

The bodies of 31 men and eight women – all from Vietnam – were found inside the truck container on Oct. 23 at the Waterglade Industrial Park in Grays, a town about 25 miles east of London. The victims ranged in age from 15 to 44, and investigators believe they paid human traffickers to transport them to England.

BRITISH POLICE MAKE ANOTHER ARREST AFTER MIGRANTS FOUND DEAD INSIDE REFRIGERATED TRUCK

Essex police said provisional postmortem examinations indicated the victims died from a combination of lack of oxygen and overheating – hypoxia and hyperthermia – in the enclosed space. Investigators are now awaiting the final reports as they continue their hunt for more suspects connected to the clandestine smuggling network.

“Our teams are continuing to progress hundreds of lines of inquiry and are working with the National Crime Agency and other law enforcement agencies from across the globe to further their lengthy and complex investigation,’’ police said in a statement.

The latest international arrests include Gheorghe Nica of Basildon in eastern England, who was detained at Germany’s Frankfurt Airport on Jan. 29. The 43-year-old faces 39 counts of manslaughter and one count of conspiracy to assist unlawful immigration.

ESSEX TRUCK DEATH VICTIMS INCLUDE 10 TEENAGERS, TWO AS YOUNG AS 15: BRITISH POLICE

A second man, who is 22, was arrested Sunday in Northern Ireland on suspicion of manslaughter and facilitating unlawful immigration. He remains in police custody in Essex but has yet to be formally charged or named.

Seven other suspects have already been arrested, including the truck driver Maurice Robinson, of Northern Ireland. He was charged last year with 39 counts of manslaughter.

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Another suspect from Northern Ireland, 23-year-old Eamonn Harrison, is being held in Ireland on charges of manslaughter and conspiracy to traffic people. He has a Dublin High Court hearing scheduled for Wednesday.

The Associated Press contributed to this report.