Six years ago, Radiohead's drum technician, Scott Johnson, died when their stage collapsed, shortly before they were due to perform in Toronto.

On Thursday night, as the band returned to the city, they demanded answers over his death.

"The people who should be held accountable are still not being held accountable," Thom Yorke told fans."The silence is [expletive] deafening."

The band then held a minute's silence before playing Karma Police.

Warning: The following clip contains language some people may find offensive

Radiohead were set to perform a sold-out show at Toronto's Downsview Park in 2012 when the stage's metal scaffolding suddenly collapsed, an hour before the gates opened.

Johnson, a 33-year-old from Doncaster, was killed and three others were injured.

A year later, police filed charges under Ontario's health and safety laws against entertainment company Live Nation, engineer Domenic Cugliari and contractor Optex Staging and Service.

All three defendants had pleaded not guilty; but the trial was "stayed" last September - meaning no charges would be brought forward - because of a landmark 2016 Supreme Court of Canada ruling that said cases in provincial court should go to trial within 18 months.

While the case had ended up in court, the trial lasted more than 40 days spread over 14 months. Then the presiding judge, Shaun Nakatsuru, was appointed to a higher court, leading to a mistrial.

Making the decision to halt proceedings, Ontario Judge Ann Nelson recognised that the outcome would be unsatisfactory for Johnson's family and colleagues.

"It is important to emphasise that timely justice is not just important to persons facing charges," she said. "It is also important to our society at large. No doubt, this decision will be incomprehensible to Mr Johnson's family, who can justifiably complain that justice has not been done."

Speaking to BBC Newsnight on Wednesday, Radiohead drummer Phil Selway said he was furious that Johnson's death had gone unexplained, meaning a similar accident could happen again.

"It's very frustrating. The court case broke down on a technicality," he said. "There have been no real answers. Without the answers we can't ensure that an accident like this doesn't happen again."

"We are assured that there is an inquest going to happen next year, so that's where we hope [to find] the real answers - stuff that everybody can act on and implement."

Selway told Canadian media that Radiohead had not felt capable of playing in Toronto again until this week.

"It's an incredibly loaded show to come back and play," he told CBC.

"There's still so much that's unresolved around the accident. Still a lot of very raw feelings about Scott, and the fact that Scott isn't here with us."