LIBBY, MT -- Fire investigators have closed their investigation, having have been unable to determine what started the fire that destroyed a former plywood plant here last February.

The blaze destroyed the operations, including equipment of Wedge Wood Products, which reportedly did not have fire insurance.

According to The Western Press, investigators ruled out heavy machinery and electrical equipment as potential causes. They also discounted "rumors that a demolition crew unintentionally caused the Feb. 26 fire with the use of torching equipment."

Investigators expressed disappointment that they could not pinpoint the fire's origin, but continued to believe "it was human-caused."