LUDOWICI, Ga. (AP) — Prosecutors say a murder case against four soldiers in Georgia has revealed they formed an anarchist militia within the U.S. military with plans to overthrow the federal government.

One of the accused troops, Pfc. Michael Burnett, pleaded guilty Monday to manslaughter and gang charges in the December slayings of former soldier Michael Roark and his girlfriend, 17-year-old Tiffany York.

Burnett told a Long County judge that Roark, who had just left the Army, knew of the militia group's plans and was killed because he was "a loose end."

Prosecutor Isabel Pauley says the group bought $87,000 worth of guns and bomb-making materials and plotted to take over Fort Stewart, bomb targets in nearby Savannah and Washington state, as well as assassinate the president.