Timothy Ray Jones Jr, 32, led investigators to the site where the bodies of the children were found, off a two-lane highway
Jones, of South Carolina, has been charged with child neglect and police expect to lodge additional charges against him in connection with the children’s deaths, authorities in South Carolina and Mississippi said.
The children ranged from one to eight years old and were reported missing by their mother on 3 September.
Jones is suspected of killing them in South Carolina before bringing their bodies to Alabama, said Wilcox County district attorney Michael Jackson.
Mr Jackson said: “These kids’ lives were snuffed out before they had a chance to enjoy life. Justice will be served.”
Police have not released details on how the children died.
Jones was being held in Smith County, Mississippi, awaiting extradition to South Carolina, the Mississippi Bureau of Investigation said. He was detained in Smith County on Saturday after being stopped at a motor vehicle checkpoint near Raleigh, Mississippi, and charged with drink-driving, Smith County sheriff Charlie Crumpton said.
Jones became agitated when a deputy questioned him about an odour of chemicals coming from the Cadillac Escalade he was driving. The deputy found what were believed to be chemicals used to manufacture meths and a substance believed to be synthetic marijuana.
A sheriff’s office investigator was called and found what appeared to be bleach, muriatic acid, blood and possible body fluids, Mr Crumpton said.
Police discovered that Jones was wanted in South Carolina “regarding a welfare concern of his children”, who were on a national missing persons list.
Investigators from several departments and the FBI started looking for the missing children on Monday. The children’s decomposed bodies were found in individual rubbish bags.
Jones had joint custody of the children and is divorced from their mother. They said he told neighbours he and the children were moving to another state.
Marlene Hyder and her husband Johnny said Jones and his wife moved into a house next to them about seven years ago in Batesburg-Leesville, South Carolina, 25 miles west of Columbia.
Two years ago, the wife moved in with a male neighbour and Jones moved away with the children, the Hyders said.
Mr Hyder said the children were often dressed in dirty clothes and were seen home at all hours of the day because Jones said he did not believe in local schools.