Clifford Carden Jr. probably was killed for his money, authorities say.
Carden, 55, was shot in the head, Sequatchie County Assistant District Attorney Steve Strain said Wednesday.
His body was found floating Feb. 3 in the Sequatchie River, about 10 miles from his burned car.
"We believe Mr. Carden was killed in the car and they dumped the body at the river, but we don't believe that he was actually shot at the river," Strain said.
He said authorities believe the killer used a 9 mm handgun, but they are awaiting ballistics tests.
Thomas Bryan Bettis, 35, of Whitwell, Tenn., and Susan Lynette Baker, 35, of Graysville, Tenn., were charged Tuesday with felony murder, especially aggravated robbery and setting fire to personal property, according to Sequatchie Sheriff Ronnie Hitchcock.
Strain said Carden once had a romantic relationship with Baker, but authorities believe that is unrelated to the crime.
"I don't think this was a love triangle or jealousy," Strain said. "That's not our theory. This was a robbery."
Authorities said no money was recovered, and they would not discuss how much might have been taken. Hitchcock said investigators have been conducting interviews to track what happened.
Strain said Carden was killed in the morning on Feb. 2. His clothed body was found the next day by a man collecting aluminum cans along East Valley Road near Pickett's Bridge. Deputies had found his burned 1996 Chevrolet Monte Carlo earlier that morning off Savage Point Road in Dunlap, Tenn.
Strain said Bettis turned himself in at the Sequatchie County Justice Center on Tuesday afternoon, while Baker was tracked down in Soddy-Daisy on Tuesday evening with the help of Soddy-Daisy police, Hamilton County authorities and state bomb and arson investigators.
Bettis and Baker have hearings scheduled this morning in General Sessions Court.
The prosecution plans to ask Judge L. Thomas Austin to continue to hold Bettis and Baker without bond, Strain said.