"During the investigation enough evidence was developed that gave us probable cause to obtain an arrest warrant (for murder)," Crosby told reporters. He said there was a development Friday afternoon that prompted them to seek the arrest warrant, but he wouldn't comment on the specifics of the case.
The medical examiner ruled that Gunn's death was a homicide, but the manner of her death has not been released.
Little, who was arrested earlier this week, had a bail hearing Friday but hadn't paid bond by the time he was charged with murder.
He will appear again in court in the next few days, David Cooke, district attorney for the Macon Judicial Circuit, said. CNN has not been able to determine the name of Little's attorney.
"He's a good son. He's a sergeant in the United States Army, serving our country proudly. Never gotten in any trouble in his life," Andre Little said. "... And he didn't do this. He always loved Anitra. ... I pray that they find the killer. ... But my son didn't do it."