With authorities ruling the fire at the West Fertilizer Co. building had been "intentionally set," new questions quickly emerged: Who? It has also been mixed with fuel oil and used in attacks, including the deadly 1995 bombing of Oklahoma City's federal building. Bryce Reed pleaded guilty to federal charges and served time in prison. Federal reports estimated that the West Fertilizer Co. had a supply of 40 to 60 tons of ammonium nitrate, a popular agricultural fertilizer that can be explosive under certain conditions. Law enforcement experts said a suspect's intent could be important as prosecutors decide whether to pursue arson, murder or domestic terrorism charges.

Source: ABC News May 12, 2016 01:15 UTC