Weaver had briefly stayed with some white supremacists, and left in disgust. The Feds (I think it was the BATF) wanted information on them, could not infiltrate them, so they chased Weaver down and ‘asked’ him to go back and be a snitch for them. Weaver nixed this. He just wanted to be left in peace on his land.
So the Feds moved an undercover agent in next door and had him be friendly towards Weaver. After a while, the guy asked Weaver to sell him a shotgun. Weaver agreed. The guy asked him to cut the barrel short. Weaver said he would not cut it shorter than the legal limit.
Weaver measured 16 inches and cut the barrel.
The Feds decided that the cut was ONE SAWBLADE WIDTH TOO SHORT, and that he had manufactured and sold an illegal sawed off shotgun. They told him they would drop the charges if he would go spy on the white supremacists.
Weaver, livid with rage over the setup and entrapment and extortion, told them to f*** themselves.
They indicted him and took him to court; the court clerk made a ‘clerical error’ sent him a notice to show up on 13 March, while everyone else got the notice to show up on 13 February. A Bench Warrant was issued when he didn't appear. Weaver decided the fix was in, that the court system was as corrupt as the Federal Agents, and told them all to f*** themselves.
The Marshalls were told to pick him up, but were so embarrassed about how it all happened that they just ignored the warrant. Eight months later a local newspaper printed a story about how the Marshals were ignoring their duty. A new manager came in and decided they couldn't ignore the warrant forever.
The story told in the article is light on details, but essentially correct from that point on.