(CNN) -- A Michigan militia leader and his son pleaded guilty Thursday to federal gun charges two days after a federal judge in Detroit dropped the more serious charges of sedition and conspiracy to use weapons of mass destruction against the government.
David Stone, Sr., 47, and his son Joshua Stone, 23, members of the Hutaree Militia, face up to 10 years in prison and a fine of up to $250,000 after admitting to possessing illegal automatic firearms. Both have already spent two years in prison.
"We are gratified that these felony convictions mean that these defendants will never be permitted to possess firearms again," said U.S. Attorney Barbara McQuade.
Federal authorities accused nine members of the "Christian warrior" militia of homegrown terrorism. The FBI planted a secret informant and FBI agent in the militia in 2008 to record the activities of the group. The video and audio recordings became the crux of the federal case, including clips of the elder Stone making anti-government statements and remarks about killing police officers.
But in a trial that began in early February, federal District Judge Victoria Roberts said she did not find that the government's evidence sufficiently proved that the Hutaree militia had planned a conspiracy against the government.
"The court's order dismissing the more serious charges in this case was disappointing, but it does not shake our commitment to dismantling groups who would harm our citizens and law enforcement officers, and these efforts will continue," McQuade said.
The move cleared several of the original nine defendants of all charges.
The Stones "admitted that they possessed machine guns, specifically a Bushmaster .223 caliber rifle and a Double Star Corp. .223 caliber rifle respectively, knowing that the firearms would shoot, and were designed to shoot, automatically more than one shot, without manual reloading, by a single function of the trigger," the U.S. attorney's office said.
Roberts, in her 28-page ruling dismissing the more serious charges, said the "government's case is built largely of circumstantial evidence."
"While this evidence could certainly lead a rational fact finder to conclude that 'something fishy' was going on, it does not prove beyond a reasonable doubt that defendants reached a concrete agreement to forcibly oppose the United States government," Roberts said.
"Pick a sentence here, pick a sentence there -- the (remarks were) taken out of context," a defense attorney for one of the cleared militia members said. "We always said it was a First Amendment and Second Amendment case, and that's what it ended up being," added attorney Michael Rataj, whose client, Tina Stone, is the wife of the elder Stone.
The Hutaree militia members cleared of all charges are Tina Stone, 46; David Stone, Jr., 22, another son of the elder Stone; Thomas Piatek, 48; Michael Meeks, 40; and Kristopher Sickles, 29. Defendant Joshua Clough, 30, awaits his sentence after pleading guilty to a weapons charge in December. Another defendant, Jacob Ward, 35, will be tried separately.
"I didn't figure we were doing anything wrong -- in the lines of going out there and doing the trainings -- to me it was basically fun," Tina Stone said Wednesday. "I'm worried for my husband and son. I guess I will be able to live my life a little easier once they're home."