Stanley Stephens, with help from Donald Luallen, set fire to the 5,900-square-foot home in the northern town of Rome on Feb. 10, police said. No one was hurt in the fire. Both are charged with first-degree arson.
Investigators from local, state and federal agencies spent more than 300 hours looking into the blaze, Fox News affiliate WAGA-TV reported.
"We guesstimate approximately $2.5 million are involved in this case," Floyd County Fire Marshal Mary Catherine Chewning said during a Thursday news conference. "This is one of the largest arson cases I am aware of in Floyd County at this time."
Stephens was arrested Monday in Daytona Beach, Fla., and Luallen was taken into custody Thursday in Oxford, Alabama. Both are expected to be extradited to Georgia. More charges against the pair are pending, Chewning said.