A Cobb County father and son who claimed to be “sovereign citizens” pleaded guilty to their roles in an organized crime that involved taking control of metro Atlanta homes they didn’t own, the county’s district attorney said Thursday.

Giulio Glenn Greye, 61, and his son, Ian Justain Greye, 34, both of Kennesaw, pleaded guilty Tuesday to violating Georgia’s Racketeer Influenced and Corrupt Organizations Act after engaging in a pattern of crimes that included burglary, theft, mail fraud and false writings, DA Victor Reynolds said.

“Ian Greye and Giulio Greye, self-proclaimed sovereign citizens, were opportunistic criminals,” John Melvin, deputy chief assistant district attorney, said in an emailed statement. “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.”

Acting as squatters, the Greyes took over homes in Fulton, DeKalb and Forsyth counties, according to investigators. In one case, the Greyes moved into a vacant home they did not own on Champlain Street in Decatur, changed the locks, and then filed false documents with the Clerk of Superior Court in DeKalb to claim ownership of the property, the DA’s office said.

Ian Greye was sentenced to 10 years, two of which he must serve in prison, Reynolds said. Giulio Greye was sentenced to five years and must also serve two years in prison.

The Greyes were among four defendants indicted in this case in 2013. The two other defendants, Susan Lorraine Weidman, 52, of Kennesaw, and Matthew Daniel Lowery, 29, of Alpharetta, are expected to stand trial in February, the DA’s office said.