The provisional results of the post mortem examinations on the 39 Vietnamese citizens discovered in the back of a lorry in Grays last year has found they died of hypoxia (deprived of oxygen) and hyperthermia (overheating)in an enclosed space.
Essex police says it is continuing to make 'significant' progress in the investigation and is looking at hundreds of lines of enquiry.
The force is working with the National Crime Agency and other law enforcement agencies from across the globe in what they say is a lengthy and complex investigation.
More arrests have been made, including some charges:
A 22-year old man in Northern Ireland on 10th February on suspicion of manslaughter and facilitating unlawful immigration. He is in custody in Essex.
A 43-year old man detained at Frankfurt Airport on 29th January has been charged with 39 counts of manslaughter and one of conspiracy to assist unlawful immigration. He'll appear at the Old Bailey in March.
A 22 year old from Northern Ireland appeared in court in Dublin on 4th February and is awaiting extradition to the UK facing 39 charges of manslaughter and charges of conspiracy to traffic people and conspiracy to assist unlawful immigration.