One of the 39 Vietnamese people who died in a container bound for the UK was recorded on a mobile phone saying “I cannot breathe”, a court has heard.
The men, women and children, aged 15 to 44, were found dead in the trailer in Essex on 23 October last year.
The Old Bailey heard Nguyen Dinh Luong, 20, was also recorded saying: “I’m sorry. It’s all my fault.” A voice in the background then says: “He’s dead.”
Two men are on trial accused of manslaughter.
One of the men, and a further two men, face people smuggling charges.
The trailer, being transported from Zeebrugge in Belgium, was found on an industrial estate in Purfleet.
Jurors have heard the victims suffocated inside the sealed trailer as the temperature reached 38.5C (101F).
Cargo operator Jason Rook said in a statement he noticed a “decomposing smell” as he unloaded the trailer at Purfleet.
He said the ship carrying it arrived at about 23:50 BST.
He said: “As I just passed the doors and reached the left hand side of the trailer I suddenly caught a strong smell that I can only describe as a decomposing smell.”
Between 22:00 and 22:30 BST it was believed that carbon dioxide in the trailer reached the “toxic threshold”, the court heard.
Jurors heard how the trailer was loaded onto the Clementine at the port of Zeebrugge at 15:00 BST on 22 October last year.
At 18:25 BST, a young Vietnamese woman took a series of selfies on her phone showing the sweltering conditions inside.
Over the next couple of hours, occupants attempted to make phone calls, with one calling the emergency number for Vietnamese police, without success.
The court heard that, in the background of one of the recordings, a voice could be heard saying: “Come on everyone. Open up, open up.”
Gheorghe Nica, 43, of Basildon, Essex, and lorry driver Eamonn Harrison, 23, deny the manslaughters of 39 Vietnamese people, aged between 15 and 44.
Mr Harrison, of Mayobridge, County Down, Christopher Kennedy, 24, of County Armagh, and Valentin Calota, 37, of Birmingham, deny being part of a people-smuggling conspiracy, which Mr Nica has admitted.
The trial continues.