A man who prosecutors say agreed to pilot a small, unseaworthy boat full of migrants illegally from France to Britain, leading to the vessel capsizing and killing at least four people, was convicted Monday of manslaughter in a landmark U.K. court case. CBS News partner network BBC News said the conviction of Ibrahima Bah was the first time a migrant had been held accountable in Britain for harming fellow occupants on one of the boats that make the dangerous crossing, or sink trying.

According to Britain’s Crown Prosecution Service, Bah could have turned the small inflatable boat around on the morning of Dec. 14, 2022, knowing that it was taking on water, but he decided to carry on across the English Channel. One passenger cited by the service said Bah told the migrants: “I will either take you there or kill you all.” 

CPS special prosecutor Libby Clark said Bah, a Senegalese national whose precise age could not be confirmed, was offered a space for free on the boat as he volunteered to pilot it, claiming to have sailing experience.

“Everyone else on the boat had paid thousands of Euros to make the tragic journey,” Clark said in a statement announcing Bah’s convictions on four counts of manslaughter. “The boat he piloted was never designed to undertake a crossing in the world’s busiest shipping lane and would have been all but invisible to other ships.”

“There is no evidence to suggest that Bah had any training in piloting a boat like this or keeping people safe and, as the pilot, he assumed responsibility for ensuring the safety of his fellow passengers,” Clark said, adding that “any reasonable person would have recognized that by piloting such an ill-equipped and overloaded boat in such dangerous circumstances, there was an obvious risk of serious harm to the passengers.”

Bah claimed during the trial that he’d been forced by smugglers to make the journey with dozens of other migrants, but Clark was quoted by the BBC as saying there was “no direct evidence of Bah being assaulted [by the smugglers] other than what Bah says,” which the prosecution deemed not to be a “tenable defense.”

“If we consider his actions as that boat went forward, he could have refused to have got in,” Clark said, according to the BBC. “He could’ve gone out in the boat for a small distance if he was in fear and then gone back because it was too dangerous in his opinion. But he kept going even when, after about half an hour into the voyage, that boat was taking on water and people were hearing sounds of puncturing and hissing as the boat deflated.”

At least four bodies were found after a local fishing boat and coast guard vessels responded to the dinghy’s distress calls. Only one of the victims has been positively identified, and at least one other person is believed to still be missing. The boat, built to carry no more than 20 people, left the shore of northern France loaded with 43 migrants, according to the CPS.

One of the surviving passengers, an Afghan man named Ahmadi, told the BBC that after first trying to bail water out of the sinking boat, he decided to plunge into the frigid English Channel to swim to the approaching fishing boat.

He said it was so cold that he felt as though he had already “died after about five minutes” in the water, and he said he saw others from the doomed vessel in the water around him.

“One person didn’t have a safety jacket. I swam over to him, but after two minutes I left him, because I realized he was dead,” Ahmadi told the BBC.

Britain’s government has been locked for months in a legal battle over its plans to curb the illegal boat crossings from France, which have soared in recent years. Prime Minister Rishi Sunak’s plan has been centered around an effort to fly many of those arriving without prior permission on U.K. shores to Rwanda, where their asylum requests could theoretically be processed remotely.

Britain’s Supreme Court ruled in November that the plan was unlawful, given “substantial grounds for believing that asylum seekers would face a real risk of ill-treatment by reason of refoulement to their country of origin if they were removed to Rwanda.”

Sunak’s government has been trying to tweak the details of the plan to get it backed by parliament and then cleared by Britain’s courts, but so far, despite millions of taxpayer dollars having been spent on the project, not a single plane has left the U.K. carrying asylum-seekers to Rwanda.