In an announcement last Wednesday, Robert Elder, Special Agent in Charge of the Houston Field Division of the Bureau of Alcohol, Tobacco, Firearms, and Explosives, announced his agency's finding that the explosion of Apr. 17, 2013 of a fertilizer storage facility in West, Texas was a "criminal act." The agency has offered a $50,000 reward to anyone having information that leads to the arrest and conviction of those responsible. No other details of the investigation's findings were released, but ATF says it has done over 400 interviews leading up to their determination that somebody deliberately set the fire that led to the explosion.
This bit of news raises more questions than it answers, not all of them technical ones. But we can ask some technical ones for starters.
The explosion itself was so violent that it showed up on seismometers hundreds of miles away, left a crater over 90 feet (27 meters) wide, and scattered debris and other evidence for miles around, besides killing 15 people and injuring about 160. How anybody could find enough evidence to conclude it was a deliberate act of arson is a good question. But the ATF people are apparently well experienced and equipped to do that. Unless and until their evidence comes out in a criminal trial, it's not possible to comment on the quality or quantity of their research and investigations. But their findings are consistent with the conclusions of the U. S. Chemical Safety Hazard and Investigation Board, which released its final report on the explosion in January of this year. In it, the Board stated that one possible cause of the fire was that it was intentionally set, although there were other possibilities as well.
If the West explosion turns out to be deliberately set, that does not reduce the need for fertilizer plants to store ammonium nitrate more safely. (Ammonium nitrate was the fertilizer material that detonated at West and caused so much damage.) A representative of the Texas Ag Industries Association made the news in April of 2015 by saying that until a definite cause for the explosion could be identified, there was no need to issue new regulations for the storage of ammonium nitrate. One hopes that now the ATF has apparently determined a definite cause, the Texas Ag Industries Association will reconsider its stance, even if it is nothing more than increasing security around existing fertilizer plants.
To those who lost loved ones or were injured or lost property in the explosion, the news that the fire was intentional can only cause more grief. We can only speculate about the motives of the perpetrator, although an ATF spokesman has ruled out terrorism as a motive. If the arsonist knew that the ammonium nitrate stored at the plant was likely to explode, the culpability in the case is compounded, but in any case, I hope that if the culprit is still around to be found, that justice can be served. I say that in the unlikely event that the person who set the fire was also a first responder who was killed in the explosion.
Such a situation is not unheard of, as the case of John Leonard Orr shows. Orr was a fire captain and arson investigator in Glendale, California in the 1980s. Following a series of suspicious fires, in 1991 a fingerprint recovered from one of the fires was found to match Orr's, and he was tried and convicted on three counts of arson. Partly because two children died in one of the fires Orr allegedly set, he was sentenced to life in prison without the possibility of parole.
I also hope that the ATF's body of evidence will withstand scrutiny in a court of law. With a special Maryland fire-investigation lab, the ATF is probably the cream of the fire-investigator crop in the U. S. But not all fire investigations are equal, and there have been cases where people have been convicted of arson with evidence that was later shown to be shoddy and insubstantial, as a 2009 New Yorker article by David Grann called "Trial By Fire" described. In that case, a man named Todd Willingham was convicted of arson in a Corsicana, Texas fire that claimed the lives of his three children. After he was executed the arson evidence was re-examined by experts, one of whom said that the original investigation was more "characteristic of mystics or psychics" than of modern scientific methods.
After all the time and effort spent on the West investigation, we can be fairly sure that the ATF would not conclude that the explosion resulted from a deliberate act unless they have strong and convincing evidence. I'm sure the residents of West are eager to hear the details of the ATF's findings, which I hope will be released in due time. But I'm sorry that after all the suffering those folks have had to go through, they now have to deal with the real possibility that someone, somewhere intended for the West explosion to happen.
Sources: This news was reported in various sources, and in particular a Houston Chronicle article by Mark Collette at http://www.chron.com/news/houston-texas/houston/article/ATF-says-West-explosion-was-a-criminal-act-7462148.php to which I referred. A video of the news conference at which Robert Elder announced the ATF's findings was posted by the Dallas Morning News at https://www.youtube.com/watch?v=mJWa3tDEYL4. The ATF's announcement of a reward in connection with the explosion can be found at https://www.atf.gov/news/pr/atf-announces-50000-reward-west-texas-fatality-fire. I referred to the U. S. Chemical Safety Hazard and Investigation Board's final report on the explosion at http://www.csb.gov/assets/1/19/West_Fertilizer_FINAL_Report_for_website_0223161.pdf. I also referred to the New Yorker website version of the article "Trial by Fire" at http://www.newyorker.com/magazine/2009/09/07/trial-by-fire and the Wikipedia articles on the West Fertilizer Company explosion and John Leonard Orr.
