Families in the UK say they are angry at the decision by prosecutors not to charge a Canadian man who is alleged to have sold a lethal chemical linked to the deaths of 73 British people.
The father of one of those who died told the BBC that Kenneth Law had caused "devastation" and that he wanted Law to face charges in the UK.
Law, a former chef, is expected to admit 14 counts of assisting suicides in Canada when he appears in court in Ontario later on Friday.
Prosecutors there say he marketed and sold lethal quantities of a substance online, which he sent to about 1,200 people around the world.
The Crown Prosecution Service (CPS) said the Canadian legal system will take the losses of UK families into account.
A letter from the CPS, seen by the BBC, said Law would not face charges in the UK because of legal complexities.
David Parfett's 22 year-old son, Thomas, used the substance said to have been sold to him by Law.
"Tom was somebody who really saw the joy in life. He would find humour in the weirdest places. I often think about his laugh," Parfett said.
"Tom was a massive football fan and he was a good footballer as well. I miss the opportunity to enjoy the 2026 World Cup with him."
Parfett said: "I had wanted Law to face charges in the UK... he really needed to face justice over here."
Parfett is calling on the UK government to hold a public inquiry into the deaths.
"I think that a public inquiry is needed because we need action across multiple government departments and unfortunately, we are not seeing that coordination and that understanding of how to address the problem today," he said.
"Fundamentally, the government is failing in its duty to protect life."
The BBC has approached the Home Office for comment.
Law was charged with 14 counts of assisting suicides in Canada and 14 counts of second degree murder following his arrest in 2023.
His capture followed a complex investigation by at least 11 law-enforcement agencies and involved investigators from around a dozen countries, including the UK, Italy and the US.
British detectives were initially investigating whether 88 deaths were linked to Law's chemical packages, but in its letter to UK families, the CPS said it believed 73 deaths could be linked to Law and that he was expected to accept sending 330 packages to the UK.
If you or anyone you know has been affected by the issues raised in this article, details of organisations offering information are available at BBC Action Line.
