As former IRA terror sympathizer turned anti-Muslim inquisitor Peter King prepares begins his Congressional hearings into Islamic radicalization, authorities have made an arrest in connection with January's backpack bomb plot in Spokane. While the identity and motivation of the suspect have yet to be revealed, the carnage narrowly avoided in Spokane could have added to the large and growing body count from right-wing terror.
The arrest in the Martin Luther King Day bomb plot was made by an FBI SWAT team executing a search warrant in the small Washington town of Addy. As the Spokane Spokesman-Review explained:

At least one person is in custody in connection with the probe of a backpack bomb planted along the planned route of the Martin Luther King Jr. Day march in downtown Spokane, authorities have confirmed...
Previously, federal officials had called the bomb a thwarted attempt at domestic terrorism and said the investigation would likely turn on forensic testing of the bomb, which had been sent to the Federal Bureau of Investigation lab in Quantico, Va.
The bomb, discovered just minutes before the start of the January 17 event, "could have inflicted multiple casualties and was placed in a way to maximize the blast toward marchers in the street." More disturbing still, "other sources then revealed that it appeared the bomb maker used rat poison, with the potential intent of causing victims to continue to bleed once struck with shrapnel."

While the suspect and his/her affiliations have yet to be announced, authorities had focused on the Aryan Nations and other white supremacist groups previously involved in other bombings in the region. The arrest follows on the heels of the death sentences handed down in December to the father and son extremists Bruce and Joshua Turnidge. The two were convicted for a 2008 bank blast that killed two policemen in Woodburn, Oregon.
So much for Peter King's fellow traveler Brian Kilmeade of Fox News, who declared last fall that "not all Muslims are terrorists, but all terrorists are Muslims."
For more background, see coverage from David Neiwert and Salon of "the terrorist attempt you've never heard of."