State investigators couldn’t find any batteries or cigarette lighters. Unlike western coal seams, West Virginia coal seldom spontaneously combusts.Investigators found several roof falls, but none close enough to have triggered the blast.So, state investigators concluded, it must have been lightning that ignited the Jan. 2 explosion that killed 12 workers at the Sago Mine.As much as anything else, the main conclusion in a new report from the state Office of Miners’ Health, Safety and Training boils down to a process of elimination.Agency investigators explored four other possible ignition sources, but said they could not find evidence that they were the cause. That left only one other explanation, and what investigators said was “strong corroborated circumstantial evidence” that lightning was to blame.“The cause of the explosion is clearly related to lightning,” says the report, which was provided to Sago victims’ families on Monday.State investigators have not been able to explain how the lightning charge got into the mine, and concede that they may never know for sure.The report has not officially been made public, though it was for several days left posted — but well hidden — on the state agency’s Web site. State officials said Thursday that mine owner International Coal Group had not officially been given a copy.One ICG miner, fireboss Terry Helms, was killed by the blast itself, which occurred at about 6:30 a.m. on Jan. 2. One crew of workers escaped, but 12 others became trapped. Eleven of them succumbed to carbon monoxide poisoning before rescuers reached then more than 40 hours later. Only Randal McCloy Jr. survived.Sago families remain furious at Wooten and his boss, Gov. Joe Manchin, for a botched effort to brief the families on the state’s report. During a private meeting Monday, Manchin stepped in and ordered Wooten to prepare a better briefing that included detailed answers to families’ questions.Since then, Wooten has refused to return media phone calls and a spokeswoman said he would not answer any questions until he meets again with the families. Other state mine safety officials also have been told not to discuss the report.So for now, the state’s report will have to speak for itself. Here’s what it says about how state investigators reached the conclusion that lightning caused the blast:First, investigators did extensive studies of burn marks, dust, and bent roof bolts to try to pinpoint the spot where the explosion started. They believe they traced it to a spot about one-third of the way into the sealed area of the mine, about 350 feet beyond the closest seal.Then, state officials examined possible causes, and ruled most of them out:s Open flames — The seals were completed 22 days before the explosion, “making it unlikely that an open flame of man-made origin could have been the source of the ignition.”“No evidence was found of any batteries, smoking materials, or other potential ignition sources in or around any area that could have been the source of the ignition,” the report said.s Spontaneous combustion — Certain coals have chemical properties that cause them to heat to the point that they smolder and eventually catch fire without an outside ignition source. In the United States, this is most common in western coals.State investigators said that coals that are susceptible to spontaneous combustion usually show signs of this early in mining, or by fires in open stockpiles or gob piles. Also, they said, spontaneous combustion would not go away after an explosion. Coal would continue to smolder, and be difficult to put out.“There has been no known history or evidence of spontaneous combustion at the Sago Mine either before or after the explosion,” the state’s report said.s Roof falls — There were numerous roof falls in the sealed area where the explosion occurred. ICG sealed the area in the first place because of repeated roof falls that made mining dangerous and difficult.State investigators found several roof falls that had occurred after the explosion, but only one that was in the region “where the balance of the evidence indicates the explosion originated.”In describing that fall, the state report says, “The domed top of the fall contains inter-bedded layers of sandstone that, under the right conditions, could have produced the necessary spark.“However, after examining this area several times since the explosion, no evidence has been found that would indicate that the ignition started there,” the report says. “The balance of the inferred propagation directions of the blast favors a point-of-origin farther to the southeast.”s Mine electrical system — After the explosion, state inspectors found more than 30 electrical violations at the Sago Mine.But the report says, “No evidence was found of any electrical equipment malfunction or failure of electrical circuits that could have caused ignition of the explosive mixture of methane and oxygen behind the seals.”The electrical violations included two citations for not having required lightning protections, but the state report provides little information about why investigators believe those problems were not related to the explosion.Also, while the conclusions of the report state, “no apparent lightning damage was found in any electrical equipment or in the electrical installations on the surface or underground,” other parts of the report detail several instances of lightning damage in the mine’s electrical systems.“Testing is still ongoing in several different areas trying to determine the cause of the explosion,” the report adds.One key piece of evidence cited by state investigators was their belief that the clock in the Sago Mine’s computer system was running nearly 5 minutes fast the day of the explosion.If the computer system time is fixed, it shows carbon monoxide monitors — indicators that the explosion had occurred — going off within fractions of a second of two large lightning strikes near the mine.Investigators and a contractor for ICG corrected the clock by comparing it to the time shown on a global positioning system unit. The contractor and a state inspector synchronized the mine computer and the GPS unit over the phone and found the mine clock was 4 minutes and 56 seconds fast, according to records attached to the state’s report.Once the mine computer was reset, its explosion warnings also matched nearly identically with a 6:26 a.m. “subtle ground disturbance” that several seismic stations recorded near the Sago Mine, the state report says.“The very close correlation of two near-simultaneous lightning strikes with the first signals from the [carbon monoxide] monitor indicating that there had been an explosion, together with corroboration of the time by analysis of a subtle seismic that originated near the Sago Mine provides strong circumstantial evidence that has led investigators to conclude that lightning was associated with the mine explosion of January 2, 2006, and most probably was the direct cause,” the state report says.To contact staff writer Ken Ward Jr., use e-mail or call 348-1702.