No other residents suffered any effects, Campbell said.
Authorities declined to identify the victim. He was a resident of the motel, but police have not determined how long he had lived there.
The DeKalb County medical examiner’s office was on the scene late Saturday afternoon and will perform an autopsy.
Police think the man died from whatever chemical was present in his room, Campbell said.
Capt. Eric Jackson of the DeKalb fire department said officials had taken “samples” of a substance in the room, but he declined to elaborate.
“Something in there made the officers sick,” Jackson said. “We have no idea what, none whatsoever.”
The firefighters who found the body left the room immediately and did not become ill, he said.
Police do not believe the man’s death was a homicide, Campbell said, but she said it was not clear yet whether his exposure to the unknown chemical was by accident or was a suicide.