The investigation by WorkSafeBC left significant evidence in the fatal fire, which occurred in January 2012 at Babine Forest Products in Burns Lake, B.C., inadmissible in court, the province's criminal justice branch said Friday.
"Based on the evidence that would likely be available for presentation by Crown counsel in court, the branch has concluded that there is no substantial likelihood of conviction for any of the regulatory offences recommended by WorkSafeBC," the statement said.
No charges will be laid under provincial workers compensation or occupational health and safety legislation. An earlier RCMP investigation ruled out criminal charges.
The concerns raised by the branch include the failure to obtain search warrants or inform witnesses of their charter rights before taking statements.
With evidence that would have been admissible, there was "a sufficient factual underpinning" for a number of provincial violations, the branch said, but the Crown felt the company had a viable defence of due diligence.
Crown lawyers met with workers and family members of the men who died in Burns Lake on Friday to advise them of the decision. Trieu Nguyen, who works at the mill, said the meeting was "intense."
"A lot of people were crying, lots of people mad," said Nguyen, whose brother was badly injured in the fire and no longer works at the sawmill.
Jeff Dolan, director of investigations for WorkSafeBC, was not available for an interview but defended the investigation in a statement posted on the agency's website.
"Our officers attended the Babine site within hours of the explosion and fire and remained at the site for 13 weeks, conducting one of, if not the largest, scene examination in the history of WorkSafeBC and the province," Dolan said.
Prior to this investigation, he said the Crown had approved charges in 31 cases investigated by WorkSafeBC between 1996 and 2010, 24 of which resulted in convictions.
The agency will release its investigative report next week.
A series of blasts and an ensuing fire at the mill on Jan. 20, 2012, killed Robert Luggi, 45, and 42-year-old Carl Charlie. Twenty other employees were injured and the mill was destroyed.
A few months later, in April 2012, an explosion at the Lakeland Mills in nearby Prince George killed 43-year-old Alan Little and 46-year-old Glenn Roche.
The investigation did not come up with a conclusive cause for the fire but did determine it ignited in the basement, setting alight combustible sawdust.
The possibilities of what started the initial fire range from an open flame to static or friction from an electric motor. Once it began, both an in-house and external expert agreed that it exploded in a violent fireball through the mill.
Though disappointed with the decision, Nguyen said he doesn't worry about working at the rebuilt mill.
"I think they learned their lesson," he said. "It was a pretty big accident. I don't think anyone saw it coming."
Burns Lake Mayor Luke Strimbold said the town is still struggling with the tragedy, and he said every development is tough on the survivors and the victims' families.
"I think people are trying to understand the decision," he said, adding community members are anxious to see the report next week.
The rebuilt mill is expected to return to full capacity next month.
Steve Zika, CEO of Hampton Affiliates, the Oregon-based owner of Babine Forest Products, said the actual cause of the explosion will probably never be known, but he said the company has worked to reduce the risk of future accidents. The new mill has equipment to collect sawdust and is designed to allow easier clean-up.
"While we are pleased no criminal or regulatory charges will be approved by Crown counsel," Zika said in a statement.
"We never will forget the terrible tragedy and the resulting effects on our employees, their families and the community of Burns Lake."
Note to readers: This is a corrected story. A previous version said WorkSafeBC would release the report on Jan. 13, instead it will be released the week of Jan. 13.