"tossing other sources of ignition" and "other cigarette" brings forth a delightful (if highly unlikely) image of hippies throwing Molotov cocktails from the vestibule. If you need to use logic instead of a fire investigator's report the concept of Occam's Razor comes to mind. If there is a fire within a few minutes after a locomotive spewing hot cinders has passed then the locomotive is certainly the most likely culprit. But we'll just have to see what the report says. The big legal question is whether the railroad took proper precautions or if running a steam locomotive under such conditions is negligence per se or even reckless. I can't imagine the possible claims from the $10,000,000 spent fighting the fire (so far) to the incovenience associated with having to evacuate one's home. The cases should clog the La Plata County District Court for years to come.
Husker Hank
Ex Legal Beagle
Durango CO