BBC viewers were in tears on Wednesday evening as they watched the documentary Hunting the Essex Lorry Drivers.
The hour-long programme detailed the investigation that took place after 39 Vietnamese people were found dead in the trailer of an articulated refrigerator lorry in Essex in October 2019.
The trailer had been shipped from the port of Zeebrugge in Belgium, to Purfleet, Essex and investigations immediately began led by Essex Police.
However, it wasn't so straightforward for the police, as their main suspects fled the UK just as they had started to piece the puzzle together.
During the 60-minute documentary, friends and family of the victims spoke to camera about their loved ones and why they had decided to move to the UK.
Viewers found it particularly hard watching them talk about how they found out about their deaths and the last text messages they received from the victims.
One of the victims had text their parents apologising and said: "My trip to a foreign land has failed. I'm dying because I can't breathe."
One mother said she still has the text message from her daughter on her phone but she has not looked at it since she found out about her death.
Speaking to camera, she said: "I don't dare look at her pictures even once," before confirming that she and her family still owe $22,000.
Some viewers found the content distressing to watch and took to Twitter to comment.
One person tweeted: "Watching 'Hunting the Essex Lorry Killers' on #BBC2 only 24 minutes in and it's heartbreaking what these traffickers did. 39 people dead....tragic."
Another posted: "Watching hunting the Essex lorry killers on TV absolutely harrowing I’m in tears and it’s just started."
A third added: "‘Hunting the Essex Lorry drivers’ was a hard watch……. Terrible story, horrible knowing they were dying & the families still having to repay the money the borrowed Be thankful for what you have!"
Someone else tweeted: "Hunting the Essex lorry killers on BBC there was such a grim watch, such a shame for the people and families of those who lost their lives."
Earlier this year, four people-smugglers were jailed for 78 years for the killings.
Ringleaders Gheorghe Nica, 43, and Ronan Hughes, 41, and drivers Maurice Robinson, 26, and Eamonn Harrison, 24, were sentenced along with three other gang members.
Nica was given 27 years, Hughes was handed 20 years in prison, Harrison was sentenced to 18 years, and Robinson was jailed for 13 years and four months - all for 39 counts of manslaughter and a people-smuggling conspiracy.
Three others were jailed for a total of 14 years for lesser offences.
Hunting the Essex Lorry Killers is available to watch on BBC iPlayer now.
