The Southern Poverty Law Center said Kevin Harpham, 36, made more than 1,000 postings on the Vanguard News Network site, many of them under the pseudonym "Joe Snuffy."
"I can't wait till the day I snap," said a 2006 message attributed to Harpham.
Harpham was arrested Wednesday after being charged with one count of attempting to use a weapon of mass destruction and one count of possessing an unregistered explosive in a case that raised worries that racist activities may be on the rise again in the Inland Northwest. Spokane and adjacent northern Idaho for several decades had been home to hate groups, although activities by such groups have dropped dramatically in recent years.
Harpham remained in the Spokane County Jail after waiving bail during a Wednesday court appearance.
Three city workers discovered the backpack bomb on a bench just before the start of the Jan. 17 parade, and it was defused without incident.
U.S. Attorney Mike Ormsby in Spokane said his office is reviewing copies of the postings, and will decide if they should be included in the upcoming indictment process, perhaps under hate-crime laws.
Harpham's lawyer, federal public defender Roger Peven, said he has heard about the Internet postings, but had not seen them. He said he would not be surprised if prosecutors altered the original charges, possibly to include hate-crime allegations.
"I would expect that what we see in the complaint is not necessarily what we will see in an indictment," Peven said.
The authenticity of the Web postings could not be immediately confirmed, but two factors pointed to Harpham as their author. In one 2008 posting, someone wrote as "Kevin Harpham" seeking technical assistance in accessing his "Joe Snuffy" account.
The other factor, according to the Southern Poverty Law Center, was that in one post, well-known white supremacist Glenn Miller wished the account's owner a happy birthday — on Harpham's actual birthday, May 1. "Happy Birthday Joe Snuffy!!!" that posting said.
The website's administrator did not immediately return e-mails from The Associated Press seeking comment.
Harpham apparently contributed financially to Miller's white nationalist newspaper, The Aryan Alternative, said Mark Potok of the Southern Poverty Law Center. In 2007, Miller wrote to Harpham on the Vanguard News Network, "You rank among the top 5-6 VNN'ers in total amount of money contributed."
In 2006, "Joe Snuffy" posted in response to video footage of anti-racists protesting white supremacists in Germany, saying it nearly made him snap. The post complained that the police cared only about the protesters and "turned their loaded guns on the neo-Nazis."
Potok said racists often use pseudonyms to hide their identities from employers and others.
The posts also displayed an interest in bombs. "Who was the person during WW2 that said something like Those who say you can't win a war by bombing have never tried,'" a 2006 post said. In 2009, another read: "I personally think we need a couple thousand pro White psychopaths then maybe we might start getting somewhere with this White Revolution."
A writing from last year that was attributed to Harpham mentioned that the mildly radioactive element thorium is useless for building bombs, and another post expressed his disappointment that the race-war novel "The Turner Diaries," by the founder of the white supremacist National Alliance, William Pierce, did not include plans for making a bomb.
Harpham was a member of the National Alliance in 2004, the Southern Poverty Law Center said.
Erich Gliebe, chairman of the National Alliance, based in Hillsboro, W.Va., told The Spokesman-Review newspaper of Spokane that Harpham is not a member of his organization, which he said believes all races are entitled to their own living spaces.
The FBI agent in charge of the Spokane office, Frank Harrill, said Thursday that bomb technicians' decision to disable the explosive, rather than detonate it, helped lead to Harpham's arrest. Investigators were able to obtain evidence from the bomb itself, he said.
He declined to specify what type of evidence was taken from the bomb.
By all indications, the Army veteran lived a quiet life on 10 acres of land north of Addy in rural Stevens County. Property records show he bought the land in 1997 and built a small house in 2007.
Harpham served from 1996 to 1999 as a fire support specialist with the Army's 1st Battalion, 37th Field Artillery Regiment at what is now Joint Base Lewis-McChord, said base spokesman Joseph Piek, who emphasized that Harpham ended his service 12 years ago.
The government's evidence will be presented to a federal grand jury on March 22. If they indict Harpham, an arraignment will be held the next day and a trial date will be set. If Harpham is not indicted, a probable cause hearing is scheduled on March 23, where federal agents must testify about the evidence they have to support the charges.
Johnson reported from Seattle.