Chelsie Berry, 24, and Jared Prier, 28, from southwest Missouri have been charged with voluntary manslaughter and abandonment of a corpse on road, police officials were quoted as saying in media reports.
Berry told police that they were high on drugs and were worried that if they took the deceased Dennis Meyer (30) to hospital, they would "get in trouble".
They drove around and dumped the body on the road before fleeing.
According to police, Meyer possibly died of a drug overdose. An autopsy has been performed but authorities were waiting for a toxicology report.