Investigators hope to determine by this what caused the explosion at a Texas fertilizer plant that killed 14 people and injured about 200, the state Fire Marshal said at a state legislative hearing on Wednesday.
Dozens of investigators remain on the ground in West, Texas, a town about 20 miles north of Waco, and more are reviewing records, officials told lawmakers this week when the first hearing was held about the blast that occurred more than two weeks ago.
"We are not expecting to finish the origin-and-cause portion of the investigation probably until about May 10," Texas State Fire Marshal Chris Connealy told the state House Committee on Homeland Security and Public Safety.
"This is a very complex event as you can imagine and we want to make sure that we do it correctly," he said.
Investigators have ruled out weather, such as a lightning strike, as a possible cause of the April 17 fire and explosion, two days after the bombings at the Boston Marathon. That leaves three possible rulings: accident, arson or undetermined.
Federal and state officials would be expected to announce their findings when they wrap up the on-site investigation, but a full report may take months to complete, officials said.
Eleven first responders, two apartment complex residents and a man who was rounding up horses were killed in the blast. A 96-year-old nursing home resident died after being evacuated.
Firefighters were called to the fire about 20 minutes before the blast, which registered as a seismic event and caused an estimated $100 million in damage.
Texas Insurance Commissioner Eleanor Kitzman said the state does not require fertilizer plants to be insured. The West plant had coverage, but its insurance had "absolutely no relationship to the amount of risk that was involved here," she said.
Democratic Representative Joe Pickett, chairman of the committee, repeatedly asked officials who ultimately was in charge of making fertilizer plants safe.
Texas lawmakers were told by top officials from several Texas state departments about a confusing array of regulations that cover hazardous materials and facilities like the West Fertilizer plant.
Texas has about 1,100 locations licensed to store ammonium nitrate, a highly explosive ingredient in fertilizer, said Steve McCraw, director of the Texas Department of Public Safety. As of last year, West Fertilizer had 270 tons of ammonium nitrate on hand.
State officials said many state regulations are geared more toward making sure chemicals like ammonium nitrate don't get into the wrong hands and monitoring the quality of products made from the materials, not assuring their safe storage.
Local fire officials are largely responsible for ensuring materials like ammonium nitrate are stored safely, said W. Nim Kidd, chief of the Texas Division of Emergency Management.
Liberal groups have used the explosion to pound Republican Texas Governor Rick Perry, who has stressed limited regulation of business as a centerpiece of his economic development plan.
Phillip Martin, political director of the liberal activist group Progress Texas, said the hearing made clear that the state lacked regulation of industrial plants and dangerous chemicals.
"Governor Perry and the Republican-controlled Legislature should heed the warnings from today's hearing and pro-actively pursue proper regulations that can mitigate future disasters like West," Martin said.
(Editing by David Bailey and Andrew Hay)