( CNN ) -- Authorities have a suspect in custody in connection with a backpack bomb found in January along a Martin Luther King Jr. Day parade route in Spokane , Washington , according to Michael Ormsby , U.S. attorney for the Eastern District of Washington . Kevin William Harpham , 36 , of Colville , Washington , was charged with attempted use of a weapon of mass destruction and possession of an unregistered explosive device , Ormsby said . Harpham appeared before a federal magistrate Wednesday and was ordered held without bail after Harpham waived his detention hearing , Ormsby said . Federal public defenders were appointed to represent him , and they will be able to ask for a bail hearing at a later date , Ormsby told CNN . Harpham lived alone in a mobile home or modified mobile home on a 10-acre tract in rural Stevens County , and the closest large city is Colville , Washington , Ormsby said . Federal prosecutors will seek a grand jury indictment against Harpham on March 22 , Ormsby said . An arraignment for Harpham is scheduled for March 23 , added Ormsby . On Wednesday , authorities were conducting a search of Harpham 's home , Ormsby said . The weapon of mass destruction charge would carry a maximum penalty of life in prison , a $ 250,000 fine and up to five years of court supervision after release , prosecutors said . The unregistered explosive device charge would carry a maximum sentence of 10 years in prison , a $ 250,000 fine and up to three years of court supervision after release , they said . The suspect was apprehended away from his home , a law enforcement source told CNN . Authorities are trying to determine if the bomb attempt was part of a conspiracy , but for now , the scheme seems to be a `` lone wolf '' situation , the source said . In January , the FBI said it would consider recent local neo-Nazi activity in its investigation of the backpack bomb . But this week , authorities still have not publicly linked the bombing attempt to any specific group or organization , Ormsby said . The bureau has been looking into the incident as `` an act of domestic terrorism , '' Frank Harrill , special agent in charge of the FBI 's Spokane field office , said in January . The investigation was aided by detailed forensic and follow-up work on the backpack bomb itself , the law enforcement source said . After the bomb was discovered , it was sent to the FBI lab in Quantico , Virginia , authorities said at the time . The bomb was found the morning of the parade in January by three workers before the event began , authorities said . The FBI released photos of the Swiss Army-brand backpack and two T-shirts found in it . One shirt says `` Treasure Island 2009 '' and the other reads `` Stevens County Relay For Life June 25th-26th 2010 . '' On Wednesday , Washington Gov . Chris Gregoire credited the three workers and law officers , saying when the Spokane 's emergency response system was put to a test , `` it worked as it should have and prevented what could have been a terrible tragedy on a day of celebration . '' `` I again want to commend the three workers who reported the suspicious backpack to authorities , and the law enforcement officers who responded , '' Gregoire said in a statement . Also on Wednesday , U.S. Attorney General Eric Holder expressed gratitude no one was injured in the bombing attempt . `` I can say that it was a viable device . It was planted with the aim of injuring or killing people . And we were fortunate that it did not go off and people were not killed . We were just lucky in that regard , '' Holder said . The device contained a chemical found in rat poison and was packed with little metal pellets , apparently as shrapnel , another law enforcement official told CNN in late January . The device was set up to be detonated remotely , that official said . The two neo-Nazi activities the FBI referred to in January occurred in nearby Coeur d'Alene , Idaho -- one on the King holiday and another three days earlier . Coeur d'Alene is 35 miles east of Spokane . Three days before the holiday , a handful of neo-Nazis in Coeur d'Alene protested two Mexican restaurants with signs saying , `` This is white land '' and `` We want you out of here . '' During the evening of the holiday , about 15 neo-Nazis demonstrated outside the Human Rights Education Institute in downtown Coeur d'Alene . The Coeur d'Alene area had been a hotbed of neo-Nazi activity through the Aryan Nations and Order II hate groups since at least the 1970s , though the groups were disbanded through criminal convictions and civil lawsuits by 2000 , said Tony Stewart , one of the founders of the Kootenai County Task Force on Human Relations in Coeur d'Alene . CNN 's Patrick Oppmann contributed to this report .
NEW : Kevin Harpham , 36 , who lived alone in a rural mobile home , is ordered held without bail . He faces two charges , including trying to use a weapon of mass destruction . A backpack bomb was found along a Martin Luther King Jr. parade route in Spokane .