Smoke billows from an Internal Revenue Service building Thursday in Austin, Texas. Authorities think software engineer Joseph Stack launched a suicide attack on the agency by crashing his small plane into the building.

Austin, Texas ? Joe Stack felt the federal government — especially its tax code — robbed him of his savings and destroyed his career while allowing corrupt executives to walk away with millions.

It’s clear from the 3,000-word manifesto posted on a Web site registered in his name that the bitter feud with the Internal Revenue Service was his passion — a passion so deeply held it apparently drove him to commit suicide Thursday by slamming his single-engine Piper PA-28 into an Austin office building that houses the IRS.

“Nothing changes unless there is a body count,” Stack wrote.

It was a passion that some of Stack’s friends say they never saw.

They knew Stack as a fellow country rocker and band mate who recorded with them in Austin’s vibrant music scene. They recalled a quiet father who visited Norway every year to visit his daughter and grandchildren. They never heard Stack talk about politics, about taxes, about the government — the sources of pain that Stack claims drove him to his death.

“I read the letter that he wrote. It sounded like his voice but the things he said I had never heard him say,” said Pam Parker, an Austin attorney whose husband was one of Stack’s band mates. “He didn’t rant about anything. He wasn’t obsessed with the government or any of that. … Not a loner, not off in a corner. He had friends and conversation and ordinary stuff.”

There was nothing ordinary about Stack’s anti-government screed. Part-autobiographical, the rambling letter references attending college in Harrisburg, Pa., a divorce and some failed business ventures in California. Mostly, though, Stack outlines his frustration with the government and the IRS. The 53-year-old contract software engineer, whose full name was A. Joseph Stack III, wrote that he spent months on the six-page diatribe in hopes it would be therapeutic.

Instead, “there isn’t enough therapy in the world that can fix what is really broken,” Stack wrote. He lamented that he couldn’t “gracefully articulate my thoughts in light of the storm raging in my head.” The end of the letter makes clear Stack’s acts were premeditated. It’s dated Thursday, with the years he lived: 1956-2010.

“I think that Joe must have been hurting really bad to take these kinds of steps to make the pain stop,” said the Rev. Patti Herndon, who married Stack and his wife, Sheryl, in July 2007.

In his note, Stack refers to several disputes with the IRS that cost him more than $40,000 and “10 years of my life.” He twice started software companies in California that ultimately were suspended by the state’s Franchise Tax Board. Stack listed himself as chief executive officer of both.

In 1985, he incorporated Prowess Engineering Inc. in Corona, Calif. In 1994, he failed to file a state tax return and was suspended in 2000 by the tax board. He started Software Systems Service Corp. in Lincoln, Calif., in 1995. That entity was suspended in 2004. Denise Azimi, spokeswoman for the Franchise Tax Board, said Stack did not pay state taxes in 1996 and 2002 — a bill totaling $1,153.

Those disputes were apparently never discussed among friends.

“I don’t know what to base his madness on,” said Michael Cerza, who played drums, piano and trumpet with Stack in The Billy Eli Band. “It must have been lurking beneath the surface.”