The State Fire Marshal's Office and the Bureau of Alcohol, Tobacco, Firearms and Explosives will announce their findings on Thursday.
Investigators have spent nearly a month combing a 93-foot-wide crater to try to pinpoint what caused the fire and the massive blast at the West Fertilizer Co. last month that killed 14 people. They have focused on ammonium nitrate, a potentially explosive chemical used as a fertilizer, as the cause of the explosion.
Texas law enforcement officials announced Friday they had launched a criminal investigation after the arrest of a West paramedic accused of possessing bomb-making materials. He has not been linked to the fire or explosion.
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