Prosecutors allege the two men are part of the so-called "sovereign-citizen" movement, which the FBI describes as a group of people who live in the United States but claim immunity from any governmental or law enforcement authority.
The elder Greye was sentenced to five years, with two to serve in prison, and the younger Greye was sentenced to 10 years, also with two to serve, by Cobb Superior Court Judge Gregory Poole.
The Greyes were charged with burglary, theft, mail fraud, false writings and other crimes, according to Cobb District Attorney Vic Reynolds, whose office also indicted two others in May under the Georgia Racketeer Influenced and Corrupt Organizations Act (RICO).
Susan Lorraine Weidman, 52, of Kennesaw, and Matthew Daniel Lowery, 29, of Alpharetta, are expected to stand trial before Poole next month.
In one of the cases, prosecutors alleged the Greyes moved into a vacant home they didn't own on Champlain Street in Decatur, changed the locks and filed false court documents in DeKalb in an effort to claim ownership of the property.
“Ian Greye and Giulio Greye, self-proclaimed sovereign citizens, were opportunistic criminals,” Cobb assistant district attorney John Melvin said.
“Our nation’s volatile housing market created a prime opportunity for a variety of mortgage fraud schemes and collateral criminal activity related to the vacant property which they broke into and attempted to illegally seize.
"They plead guilty to racketeering including the underlying acts of mail fraud, burglary, false writings and theft. Judge Poole sent a clear message in his sentence that Cobb County will not tolerate this nonsense.”