The former college student and house-framer from Foresthill was so dangerous that, after a 10-day trial in Sacramento in 2007, he was sentenced to nearly 20 years in federal prison in a case touted by the FBI as a shining example of its success in fighting domestic terrorism.

Then, the government changed its mind, conceding that thousands of pages of evidence that should have been given to McDavid's defense attorney years ago – including love notes to a young woman who turned out to be an FBI plant – had instead been secretly held in an FBI file....