The man accused in the failed Martin Luther King Day bomb plot in Spokane, Wash., has reported links to the white supremacist movement, including a past membership in a neo-Nazi group.
Kevin William Harpham, arrested Wednesday and charged with attempting to use a "weapon of mass destruction" in the foiled Jan. 17 plot, appears to have made over 1,000 posts on online forums at the extreme rightwing website Vanguard News Network.
Harpham, who apparently posted under his own name and then an alias, was active in the forums until a day before the bomb scare. More than a week before that, Harpham was one of several users who offered to house prominent white nationalist Craig Cobb. Cobb is on the run from Canadian authorities for alleged hate crimes and had called his supporters to launch violent attacks in the name of white supremacy, according to a report by The Vancouver Sun.
Harpham never mentions the Spokane plot in dozens of his most recent posts, which were first reported by Media Matters.
Harpham, 36, was also a member of the neo-Nazi group National Alliance in 2004, according to a report by the Southern Poverty Law Center, which tracks hate groups. A spokesman for the National Alliance told ABC News Harpham is not listed among their current members.
The FBI said Wednesday investigators were looking into the possible links between Harpham and white supremacist groups and today Michael Orsmby, the U.S. Attorney handling the case, said there could be other suspects.
"We don't know enough at this point to know if there are other individuals or other organizations involved," Orsmby said.
The Southern Poverty Law Center estimates there are 21 different "hate groups" in the region, but the Center's director, Mark Potok, said it was "extremely unlikely" the attack was planned by a group.
"The vast majority of these types of attacks are carried out by lone wolves," Potok told ABC News. "It's extremely probable this man was acting on his own or with one or two confederates."
Early in the investigation, the FBI special agent in charge Frank Harrill said the attack was almost certainly race-related.
"I think the connection is virtually inescapable," Harrill said then.
Harpham appeared in federal court shortly after his arrest Wednesday. Roger Peven, the federal defender assigned to Harpham's case, did not wish to comment on the case except to say his client is taking the charges against him very seriously.
If convicted, Harpham could face life in prison.
Holder: 'We Were Just Lucky' Bomb Didn't Kill Anyone
Just half an hour before the parade was due to begin on Jan. 17, three city workers reported seeing a backpack with wires sticking out, the FBI said during its initial investigation.
Authorities rerouted the parade while officers from the Spokane Police Department's bomb disposal unit worked on the bomb.
U.S. Attorney General Eric Holder said Wednesday the bomb "was planted with the aim of injuring or killing people."
"We were fortunate that it did not go off and people were, in fact, not killed. We were just lucky in that regard," he said in a press conference.
The bomb, described as a small pipe bomb, was designed to be triggered by a radio frequency system, and was directional -- meaning it was designed to spray its deadly shrapnel in the direction it was pointed, law enforcement sources said. Aimed at the parade route, it could have caused multiple casualties among the marchers. About 1,500 people showed up for the parade.
"The potential for lethality was clear," Harrill said.
ABC News' Richard Esposito and Neal Karlinsky contributed to this report.
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