Suspicious fires are handed over to the RCMP to investigate... I am trying to remember what the Fire Marshall does in BC... *checks google* right... The Fire Marhsall in BC is actually know as the Fire Commissioner office... their task (taken right from the website) is as such
"The Office of the Fire Commissioner is the senior fire authority in the province with respect to fire safety and prevention. Services include administration and enforcement of fire safety legislation, training of local assistants to the fire commissioner, fire loss statistics collection, fire investigation, fire inspection, response to major fire emergencies, advice to local governments on delivery of fire protection services, public fire safety education and fire fighter certification."
Hope that helps