Two men have been found guilty of the manslaughter of 39 Vietnamese migrants found dead in a lorry trailer in Essex.
The migrants suffocated in the sealed container en route from Zeebrugge to Purfleet in October 2019.
Eamonn Harrison, 24, who dropped off the trailer at the Belgian port, and people-smuggler Gheorghe Nica, 43, were convicted by an Old Bailey jury.
Two others were convicted of being part of a wider people-smuggling conspiracy.
The trial examined three smuggling attempts by the gang - two that were successful on 11 and 18 October, and the final trip on 23 October.
Lorry driver Christopher Kennedy, 24, from County Armagh, collected the trailers from Purfleet on the earlier two runs, claiming he thought he was transporting cigarettes.
But the jury found Kennedy and Valentin Calota, 38, of Birmingham, guilty of conspiring to assist illegal immigration.
During the trial, jurors were given a snapshot of the victims - who included a bricklayer, a university graduate and a nailbar technician - and their dreams of a better life.
Many of their families borrowed heavily to fund their passage, relying on their potential future earnings once they got into the UK.
Det Ch Insp Daniel Stoten, from Essex Police, said: "If you look at the method, the way they transported human beings... we wouldn't transport animals in that way."
Another two men - Irish haulage boss Ronan Hughes, 41, of Tyholland, County Monaghan, Ireland, and 26-year-old lorry driver Maurice Robinson - had previously admitted manslaughter.
Home Secretary Priti Patel described the deaths as a "truly tragic incident".
Prosecutors said in the fatal run, the container became a "tomb" as temperatures in the unit reached an "unbearable" 38.5C (101F).
The migrants, aged 15 to 44, were sealed inside for at least 12 hours.
They had used a metal pole to try to punch through the roof, but only managed to dent the interior.
Prosecutor Bill Emlyn Jones said: "There was no way out, and no-one to hear them; no-one to help them."
Harrison, of Newry, County Down, towed the trailer to Zeebrugge, from where it was transported to Purfleet.
During the 10-week trial, he claimed he did not know there were people in the trailer and that he watched "a wee bit of Netflix" in bed as they were loaded on.
He also said he had no idea there were migrants in two other trailers that he had dropped off at the same port in the previous 12 days.
Robinson, from County Armagh, collected the trailer when it arrived on UK shores just after midnight on 23 October.
His boss, Hughes, had messaged him: "Give them air quickly don't let them out.". Robinson gave a thumbs-up in reply.
But when Robinson stopped on a nearby industrial estate, he found that the migrants were all dead.
There was a series of telephone conversations between him and Hughes and Nica, of Basildon, Essex, before Robinson eventually dialled 999.
In his evidence, Nica said Robinson told him: "I have a problem here - dead bodies in the trailer."
Det Ch Insp Stoten said that many of the police officers who attended "were really young in service" and it was possibly the first time some had ever seen a dead person.
He said he believed the "absolutely horrendous scene" would stay with those officers "for the rest of their career and, quite probably, the rest of lives".
On all three runs, Nica had arranged cars and a van to transport the migrants at the UK end.
Jurors were shown CCTV footage of him carrying a holdall of cash to Hughes's room at the Ibis hotel, Thurrock, early on 19 October.
Nica admitted to conspiring to assist illegal immigration in the first two runs, but he insisted that he believed the third run was all to do with smuggling cigarettes.
The mechanic told jurors he had been roped into people-smuggling, and said: "I never wanted to be involved in this kind of job."
The day after the bodies were found, Nica travelled to Romania, claiming he was "scared" of a "big, big investigation", but prosecutors said the defendant's version of events was "ridiculous".
Det Ch Insp Stoten said the gang stood to make between £10,000 and £12,000 per person transported, "the lion's share of which would have gone to Ronan Hughes and Gheorghe Nica".
The jury had heard that on 14 October, between the two successful runs, Kennedy was found at the French end of the Channel Tunnel with 20 Vietnamese migrants in his trailer.
At least two of those people ended up dying in the fatal run.
Police believe the smugglers had "doubled-up" the load on 23 October because of the problem on 14 October, and that was what led to the deaths.
Analysis by Daniel Sandford, BBC Home Affairs Correspondent
This gang had been smuggling people for months and months, the Old Bailey heard.
On the first of several successful runs on the same route, a couple, Marie Andrews and Stewart Cox, saw people getting out of a van on a country lane in Orsett, Essex, and dialled 999.
Police attended but did not seize CCTV footage from the nearby golf course, in which a lorry and other vehicles were seen on the lane.
If, perhaps, Essex Police had managed to get to that footage, follow it up and identify some of the vehicles before the fatal run 12 days later, then this gang might possibly have been disrupted before these 39 people died.
Asked about that, the force said it could only allocate the resources available at the time.
But it says that now, if there are ever reports of people in the back of a lorry and the driver is present, the driver will be arrested.
Alexandru-Ovidiu Hanga, 28, of Hobart Road, Tilbury, Essex, and Gazmir Nuzi, 43, of Barclay Road, Tottenham, north London, had earlier admitted assisting unlawful immigration linked to the case.
Mr Justice Sweeney adjourned sentencing of all the defendants to 7, 8 and 11 January.
Ms Patel said her "thoughts remain with those affected by this tragedy".
"Today's convictions only strengthen my resolve to do all I can to go after the people-smugglers who prey on the vulnerable and trade in human misery," she added.