Joseph Stack, the 53-year-old software engineer who crashed his small plane into a seven-story office building in Austin, Texas, was part of a growing, violent anti-tax and anti-government movement that has become increasingly alarming to law enforcement agencies.
Stack, who torched his home Thursday morning before setting out on his suicide flight, was fueled by his hatred of the Internal Revenue Service, which had offices and employed nearly 200 workers in the building.
In his wake he left a rambling and lengthy online manifesto in which he railed against big government, bank bailouts and the IRS and revealed his decades-long involvement in the anti-tax movement and the evolution of his beliefs.
Experts are pointing to the incident as further evidence of what they say is a proliferation of anti-government militia groups.
"There is a real rage out there, and this terrible attack may be a reflection of that," Mark Potok, the director of the Southern Poverty Law Center's Intelligence Project, said in a statement to FOXNews.com. The SPLC has been studying the resurgence in anti-government militias and groups, which it attributes to a perfect storm of economic, political and social factors.
"There's been an explosive growth of anti-government militias and so-called Patriot groups over the past year, and the central idea of many of them is that taxes are completely illegitimate," Potok said.
There was an immediate response to Stack's violent act on anti-government and anti-tax blogs, and on Facebook, where multiple fan pages attracted hundreds of followers within hours of the plane crash.
"Half of them are making this guy into a hero, that's scary stuff. The other half is saying that this guy's a victim," said J.J. MacNab, a Maryland-based insurance analyst who has testified before Congress on the anti-tax movement and is writing a book on the subject.
She said anti-tax, anti-government protesters did not condone Stack setting his house on fire, "but the tax protest movement is not condemning him."
Tax protesters have a history of violence against the IRS, MacNab said. But she said Stack's method of attack - a suicide mission - was unusual. The anti-tax protester's favorite weapon, she said, is a bomb.
"He is not your typical tax protester, but he got angry like the rest of them," MacNab told FOXNews.com. "He's had lots and lots of tax problems, spanning back to the mid-1980s."
According to the SPLC, there were five domestic terrorist plots against the IRS between 1995 and 2009; an IRS building in Austin was the target of a plot 15 years ago.
"In the 1990s, the combustible mix of rising antigovernment anger and the growth in militias was a recipe for disaster that ultimately resulted in the bombing of the Murrah Federal Building by Timothy McVeigh, who was motivated by antigovernment hatred," read a blog post on SPLC's Web site after Stack's attack.
Stack's manifesto offers insight into his personal journey as a tax protester - and into the large and growing movement that attracted him.
Passages of Stack's manifesto suggest that he was involved in a notorious home church scheme that was popular in the part of California where he lived before he moved to Texas, MacNab said.
Stack wrote that he was part of a group who held tax code readings and "zeroed in on a section relating to the wonderful 'exemptions' that make institutions like the vulgar, corrupt Catholic Church so incredibly wealthy."
He said they had "the best high-paid experienced tax lawyers in the business."
MacNab said Stack likely was referring to a notorious scheme run by lawyers William Drexler and Jerome Daly. It was based on the idea that citizens could establish themselves as a church and gain the same tax exemptions afforded to religious institutions.
The scheme didn't work, and Drexler and Daly were disbarred and imprisoned. If this was the operation Stack was referring to, it may have been a turning point in his life. He wrote:
"That little lesson in patriotism cost me $40,000+, 10 years of my life, and set my
retirement plans back to 0. It made me realize for the first time that I live in a country with an ideology that is based on a total and complete lie."
This inspired him to take action, write to politicians and meet with likeminded anti-tax protesters. He wrote: "I spent countless hours on the L.A. freeways driving to meetings and any and all of the disorganized professional groups who were attempting to mount a campaign against this atrocity."
His anti-tax and anti-government beliefs may also have been fueled by Section 1706, an obscure and relatively unknown change in the tax code that focused on his industry and went into effect in 1986. Section 1706 essentially removed technical workers like software engineers from a safe haven classification of "self-employed consultant," making it easier for the IRS to challenge how Information Technology companies classified their employers.
An association of IT companies and industry professionals, now called TechServe Alliance, was created to protest the changes in tax law that it says singled out the industry.
"It made the whole business riskier for people using independent contractors because it favored the so-called employment business model," Mark Roberts, TechServe CEO, told FoxNews.com. "It created havoc on a number of folks."
Roberts was quick to condemned Stack's behavior as "an act of a very, very sick individual."
"I don't see a long-term lasting effect, just a troubled wayward person acting in response to a legitimate issue. But I don't think that actually impacts the issue," Roberts said.
Noting that Section 1706 was passed years ago, he added: "We still resent the fact that it singles out the industry, but folks have basically learned to adapt. It's kind of been awhile since this was a burning issue in the industry."