Authorities still are waiting to learn what killed a 9-year-old boy whose body was found in the back of a Jeep stuck in the middle of the Sequatchie River.
Marion County Sheriff Ronnie "Bo" Burnett said state and local investigators need results of the autopsy on Zachary Taylor Henry before proceeding in the investigation.
Though there's no known cause of death yet, and Burnett said he doesn't believe the boy drowned.
When the cause of death is determined, it will lead to the next steps, 12th Judicial District Attorney Mike Taylor said.
"What killed him is sort of the mystery right now," Taylor said.
A blood toxicity test could show whether Zachary died of something coming from the running Jeep - such as carbon monoxide - or whether he ingested something toxic, Taylor said.
"We probably won't get the final report for another two or three weeks," he said.
Meanwhile, Zachary's mother, Lindsey Newsom, 27, and her boyfriend, Nicholas Mosier, 30, are being held without bond on charges of felony reckless endangerment, felony child abuse and illegal possession of prescription drugs.
Mosier, who was driving the Jeep when it ended up in the river on Oct. 6, also is charged with driving under the influence of an intoxicant and driving on a revoked license, the sheriff said.
Burnett said the issue of the pair's bonds could come up in court hearings this week.
Newsom and Mosier were arrested after authorities checked out a 911 call about a Jeep stuck in the Sequatchie River north of Whitwell, Burnett said. When officers arrived, they removed Newsom from the Jeep, then spent considerable time getting Mosier to leave the vehicle.
Mosier was still trying to drive the Jeep out of the river, where it was sitting in about three feet of water that just reached the vehicle's floorboards, Burnett said.
It was only after Mosier was taken to the riverbank that he asked officials about Newsom and her son, he said.
"That's when they found Zachary Henry deceased in the back of the Jeep," the sheriff said.
Burnett said that, as far as officials could tell, Newsom and Mosier and Zachary had been riding the Jeep around that section of the river, a popular location for all-terrain and off-road vehicles.
TBI agents and the Tennessee Highway Patrol's criminal investigations division are leading the investigation, the sheriff said.