Arson was the official cause of the fire that destroyed the house belonging to the man who flew his plane into an office building, Austin fire officials said Thursday.
Austin Fire Department spokesman Andre de la Reza said investigators determined the Feb. 18 blaze at Joseph Stack's home was intentionally set. Authorities previously have said they believed he started the blaze, drove to a nearby airport and then piloted the suicide flight into the complex that houses offices of the Internal Revenue Service.
Shortly after the crash, authorities found a rambling manifesto from Stack in which he described a long-smoldering dispute with the IRS and a hatred of the government. The family's accountant has confirmed that the Stacks were in the middle of an audit for reportedly failing to report income.
IRS employee Vernon Hunter, 68, was also killed in the crash. On Monday his family sued widow Sheryl Stack, to determine if her husband had insurance policies or other assets, according to Hunter attorney Daniel Ross. Services for Hunter were set for Friday.
Neighbors have set up a Web site seeking financial assistance for Sheryl Stack and her daughter, 12.
"This site was set up by neighbors of the Stacks in the Scofield Farms neighborhood in Austin, Texas. It is intended to help support Sheryl and her daughter in their time of need," according to a message Tuesday on the Web site.