He was a 53-year-old software engineer who played bass in a local band and lived what by all appearances was a quiet suburban life here with his wife, who taught piano at home, and her young daughter. But, for several decades, Joe Stack also had been battling the Internal Revenue Service -- and nursing a grudge.
And on Thursday morning, he acted.
After setting fire to the family home, he drove to the municipal airport, slid into the cockpit of his single-engine Piper Cherokee and took off into the clear blue sky over Austin, authorities said. Fifteen minutes later, just before 10 a.m., he piloted his plane into the seven-story building where 190 IRS employees work in the state capital, igniting a fire that killed him and one other person and seriously injured two workers, authorities said.
The FBI said late Thursday that two bodies had been found in the building, but they had not been identified. In addition to Stack, they said, one federal worker was missing and presumed dead.
A billowing plume of black smoke rose from the building in the Echelon office park throughout the day, a vivid reminder for many of the Sept. 11 attacks in New York. The impact sent a fireball blooming up from the ground floors, and the explosion sounded like a sonic boom, shaking nearby buildings.
A person identifying himself as Stack wrote in a rambling, 3,000-word Web treatise that "I'm finally ready to stop this insanity . . . Well, Mr. Big Brother IRS man, let's try something different; take my pound of flesh and sleep well."
The note, which he called a "rant," began: "If you're reading this, you're no doubt asking yourself, 'Why did this have to happen?' The simple truth is that it is complicated and has been coming for a long time." It was signed, "Joe Stack (1956-2010)."
The note included a litany of complaints about the tax authorities, organized religion, government bailouts and "sleazy" accountants, and a life story that included a divorce, lost jobs and struggling businesses. Stack moved from Southern California to Austin, where he remarried in 2006, hoping to find work as an engineer.
But, the note said, "I've never experienced such a hard time finding work."
The FBI is leading the investigation of Stack, and officials would not comment on the Web post. Authorities said they had no evidence that Stack's actions were related to any international terrorism group.
"It's an isolated incident," Austin Police Chief Art Acevedo said.
The morning attack occurred in an office building campus once considered one of Austin's finest, next to a well-groomed neighborhood that is home to many of the professionals who flocked here to take advantage of the tech boom of the 1990s.
Some workers in the building saw the approaching plane and warned others. "There were some heroic actions on the part of some employees," Acevedo said.
Stack's two-story home on Dapplegrey Lane caught fire shortly after 9 a.m., Austin fire officials said. Neighbor Carlotta Hutchins said she heard a loud blast, ran outside and saw smoke pouring from the Stacks' home. "It's pretty much a shell right now," she said.
Hutchins said she didn't think Stack's wife, Sheryl, or her daughter, who is about 12, were home at the time. Fire officials later said neither was injured.
The neighbor described the Stacks as friendly and, outwardly at least, the family did not appear to be struggling financially. The home, purchased in 2007, was assessed at $232,066, according to property tax records. Stack also was the registered owner, in Placer County, Calif., of the Piper aircraft.
Reached by telephone in Hemet, Stack's ex-wife, Ginger Stack, to whom he was married for 18 years, said: "He was a good man. Frustrated with the IRS, yes, but a good man."
His anger at the IRS stemmed from changes Congress made to the tax laws in 1986, she said, which he considered unfair because they changed the way businesses treat independent contractors.
"I'm in shock right now," his ex-wife said between sobs. "He had good values. He really did." She said her ex-husband was an "extremely intelligent" man who also had helped raise her daughter, whom he had given away at her wedding.
Though much of Stack's life remained a mystery, his note and California tax records suggested a long-running battle with the government.
He and Ginger Stack in 1985 launched Prowess Engineering Inc., which listed an address in Chino Hills. In 1993, using the name A. Joseph Stack, he filed state documents that listed himself as chief executive of Prowess, which was described as a software engineering company in Corona. Two years later, he filed paperwork to incorporate Software Systems Services Corp. at the same address. Later, his companies listed an address in Placer County, near Sacramento.
The California Franchise Tax Board issued a suspension of Prowess in 2000 for not filing a 1994 tax return, which means the company cannot operate or collect money for services. Software Systems received another suspension in 2004, for not paying taxes in 1996 and 2002, according to Denise Azimi, a spokeswoman for the board.
Ginger Stack filed for bankruptcy in 1999, the year their divorce was finalized, citing an inability to pay $125,860 in taxes owed the IRS for 1993 and 1998.
An IRS spokesman declined to comment on Stack's tax grievances. Independent accounts by experts who read Stack's farewell note said he appeared to have many tax problems that could have triggered IRS scrutiny.
Stack, in his Web posting, said he drained his retirement account after leaving California and, because he hadn't had any income that year, didn't file a return.
"The sleazy government decided that they disagreed," he wrote, and he said he was assessed $10,000.
In Austin, Stack and his family lived about a 15-minute drive from the crash site in Scofield Farms, a neighborhood of modest houses inhabited by new arrivals over the last couple of decades as Austin's fortunes boomed.
The Stacks were in many ways a typical Austin family: he an engineer, and she a musician. Neighbors said Sheryl gave piano lessons and was working on her doctorate in music.
Natalie Kunkel, 33, who lived two doors down, was on friendly terms with Stack, his wife and her daughter. Sheryl Stack is outgoing, whereas her husband was reserved. "They seemed like a normal, typical family," Kunkel said.
It wasn't clear whether Stack had a full-time job in Austin, and he may have worked as a consultant.
Soon after moving to Austin in 2004, Stack played bass for two years in the Billy Eli Band, which recorded an album, "Amped Out." Ric Furley, the drummer, said he hadn't talked much to Stack since then, but he remembered him as a dependable guy with a good sense of humor.
"He didn't have an attitude. He didn't try to one-up anybody. He was the perfect bandmate," Furley said. "I never saw him angry. I have no way to relate to him as an angry human being."
Stack never railed about politics or the government. "I don't even know where he stood politically," Furley said. "He was the nicest guy. He didn't seem to have any issues."
Times staff writers Ashley Powers, Richard A. Serrano, Kathy M. Kristof, Corina Knoll, Robin Abcarian and Scott Kraft contributed to this report.