Joseph Jeffrey Brice, injured in the mishap last April, has already been charged with manufacturing the bomb.
The FBI Joint Terrorism Task Force executed search warrants last week on homes and cars associated with Brice, The Seattle Times reported Friday.
Brice, 21, now may be accused by federal prosecutors in Spokane, Wash., of maintaining a Web site bearing marks of extremist Islamic terrorist groups, including al-Qaida, the Times said.
Officials allege Brice created a YouTube channel called "StrengthofAllah" where jihad-related content, including bomb-making tips, were posted. A plot was uncovered involving using a bomb as a distraction to rob a nearby bank, officials allege.
Prosecutors now are weighing evidence to decide whether to charge him with manufacturing a weapon of mass destruction and rendering material support to terrorists, the newspaper reported.