ATF: Spark caused deadly cannonball explosion Associated Press - August 11, 2008 1:53 PM ET RICHMOND, Va. (AP) - Federal investigators confirm that a Civil War relic hunter was killed by a cannonball earlier this year. They say the 53-year-old Virginia man was cleaning the nine-inch cannonball with a grinding tool when a spark ignited it. The blast killed the man and sent part of the cannonball a-quarter mile away, through the roof of another suburban Richmond home. Bureau of Alcohol, Tobacco and Firearms experts say there was evidence the century-old shell had been made inert. But there was apparently still enough explosive powder inside to cause a deadly blast.