Matthew Carr-Gomm, who has been living in New Zealand since 2003, said it was hard to believe two deaths at retreats organised by Xiao were coincidental.
"There has to be responsibility. The fact that it's happened twice can't be put down to 'it's just an accident'."
Carr-Gomm said his mother, who'd been diagnosed as a diabetic when she was 58, appeared very healthy when he last spoke to her.
"I have all sorts of questions about the circumstances that led to what happened," he said.
"It could have happened to anyone."
He was not aware of the exact details of what happened the night his mother, Danielle, had died, but hoped Xiao's arrest could lead to answers.
"In terms of justice, on one level what's done is done - I'm never getting my mother back."
Carr-Gomm believed, "without a shadow of a doubt" his mother would still be around if she hadn't gone to the course run by Xiao.
"She certainly had plenty more years in her," he said. "This is one of those things which is really hard in hindsight. We all undervalue our relationship with our parents - when they are gone it's a bit too late.
"There are plenty of moments I reflected and gone, it would have been nice to have done this with her."
Carr-Gomm said the news of Xiao's arrest in the United Kingdom was a great relief.
"I think the thing that has concerned us most is the fact that he has continued to practice and run workshops across the world."
He said what had happened to his mother highlighted the real danger presented by a person who is a non-medical professional and advises against official medical advice.
Carr-Gomm said his mother was typically very healthy and was meticulous with taking her insulin and would have just taken the practitioner at his word.
