Crown prosecutors have decided not to lay charges in the April 2012 wood dust explosion and fire that killed two workers in Prince George.

The Criminal Justice Branch issued a statement Monday saying the evidence available for court would be unlikely to result in a conviction. There is evidence of prohibited acts recommended for charges against mill operators, but a defence of “due diligence” would likely result in acquittal, the statement says.

WorkSafeBC had recommended two charges for alleged violations of the Workers Compensation Act and two more for violations of the Occupational Health and Safety Regulations in the Lakeland blast. No criminal negligence charges were recommended.

All four recommended charges are regulatory offences, with conviction resulting in fines. Prosecutors found that WorkSafeBC did not use “major case management” procedures, including search warrants and gathering evidence on the state of management’s knowledge of the risk.

A similar conclusion was reached in the case of the Babine Forest Products mill in Burns Lake, where prosecutors determined they would be unlikely to prove negligence. Administrative penalties totalling more than $1 million were levied on the Babine mill owners.

Labour Minister Shirley Bond announced Monday that a coroner’s inquest will be held into the Lakeland fatalities. B.C. Ferries Commissioner Gord Macatee is temporarily replacing outgoing WorkSafeBC CEO David Anderson and will oversee changes to worker protection and investigation, Bond said.

Two mill workers died and 20 others were injured when an explosion and fire tore through the Babine sawmill on Jan. 20, 2012. A similar blast three months later killed two workers and injured 22 more at Lakeland Mills.

Investigators ruled out natural gas, oil and other fuel sources, leaving fine, dry dust produced from milling dry wood. The likely ignition source was hot electric motor and gear reducer equipment running wood waste conveyors in low, confined areas of the mills.

Extra efforts to inspect mills for dust accumulation were underway across the province when the Lakeland fire occurred. Both mills were processing large volumes of dead trees killed by the mountain pine beetle.

The Crown counsel report described a smaller dust fire at Lakeland on Jan. 19, 2012, when sparks from an equipment malfunction ignited “a column of burning sawdust that rose to the ceiling.”

No one was hurt in that incident, and spot fires in sawdust were put out by mill workers.

In the five years preceding the fatal explosion, WorkSafeBC issued 36 inspection reports and cited Lakeland for 15 violations, but none were related to sawdust. There were no warning letters or administrative penalties to Lakeland for sawdust issues during that time.