The driver who dropped off a lorry container carrying 39 migrants who were later found dead told a court he was “devastated” for their families.
Eamonn Harrison towed the trailer to a Belgian port, where it was transported to Essex. When opened on 23 October 2019, it was found to have the dead Vietnamese migrants inside.
Mr Harrison told jurors at the Old Bailey he did not know they were there.
The 23-year-old, of Newry, County Down, denies manslaughter.
The court had previously been told the victims, aged 15 to 44, suffocated in the sealed trailer en route from Zeebrugge to Purfleet in Essex.
Irish haulier boss Ronan Hughes, 41, and lorry driver Maurice Robinson, 26, have previously admitted manslaughter.
Mr Harrison told a jury he had suffered from Attention Deficit Hyperactivity Disorder (ADHD) which meant he struggled at school and found it hard to make friends.
However, he added he had “loved” his work as a lorry driver, a job he started at the age of 18.
He said when he met Mr Hughes he was “a gentleman”, and he started to work for him.
In May 2019 Mr Harrison crashed his lorry when driving while drunk in Germany, writing off the tractor unit and damaging the load, the court was told.
Jurors heard after that he owed Mr Hughes £16,000 and he agreed to help with “stolen goods jobs”, agreeing that he would “walk away” when the lorry was being loaded and come back 15 minutes later.
Asking about the events of October 2019, Mr Harrison’s barrister, Alasdair Williamson QC, said: “You drove the tractor unit that pulled the trailer that contained 39 people on their way to their deaths. How do you feel about that?”
Mr Harrison replied with an expletive for bad.
Asked how he felt for the families, he said: “Devastated.”
Mr Williamson then said: “Did you know that there was anyone on your trailer?”
The defendant replied: “No.”
Mr Harrison and Gheorge Nica, 43, of Basildon, Essex, deny 39 counts of manslaughter.
Mr Harrison, lorry driver Christopher Kennedy, 24, of County Armagh, and Valentin Calota, 37, of Birmingham, have denied being part of a wider people-smuggling conspiracy, which Nica has admitted he was involved in.
The trial continues.