Sgt Joseph Bozicevich, 39, has been returned to the US from Iraq and is being held in pre-trial confinement at an undisclosed location in southern Georgia.
Bozicevich is charged with the September 14 slayings of Army Staff Sgt Darris Dawson, 24, and Sgt Wesley R Durbin, 26. Written charges filed against Bozicevich say he shot both soldiers with a rifle.
Maxine Mathis, Dawson's stepmother in Florida, said she wasn't rushing to judgment.
"I don't want to condemn him," Mathis said. "I don't know what state that child was in. He's somebody's son, too."
Bozicevich's father, who lives near Albany, New York, said he hadn't heard from his son much since his unit deployed to Iraq last year. He said he was unaware his son faced criminal charges until a reporter contacted his family yesterday evening.
"We just have to wait and see what the circumstances were," said Joe Bozicevich Sr, the soldier's father. "In a combat zone, where people are highly stressed, who knows what happened?"
The soldiers were serving a 15-month deployment to Iraq with the 4th Brigade Combat Team of the Army's 3rd Infantry Division.