So far, there is no suspect but authorities have concluded the killings in four different locations are related, Tennessee Bureau of Investigation spokeswoman Kristin Helm said Wednesday.
Investigators in Lincoln County, Tenn., and Madison County, Ala., have found that one of those who died, 24-year-old Warren Vincent Crutcher, knew the other victims and may have been involved in the slayings at two homes in Lincoln County, Helm said.
"We have evidence that these two Lincoln County crime scenes are related, and that Crutcher was involved to some extent in those," Helm said. "Did he act alone? That's what we are trying to figure out."
Crutcher, however, also was slain. "Someone is responsible for his murder," Helm said.
The investigation of the complicated case began Monday. That's when a 3-year-old boy called relatives from a house outside Fayetteville saying he couldn't wake up anyone in the home, the boy's godmother, Constance Winston, told Huntsville, Ala., television station WAFF.
Family members arriving at the house, about 100 miles south of Nashville, found all the doors and windows locked, but were able to coach the child into opening a garage door. When they reached inside to pull him out, they saw blood and called police.
When authorities got there, they found the bodies of 22-year-old Chabreya Campbell, and her 18-month-old son, Rico Ragland. The body of 21-year-old Amber McCaulley, of Huntsville, Ala., was also inside the home.
Hours later, the body of 21-year-old Jessica Brown was found in her home in Fayetteville. Her 2-month-old child was discovered unharmed.
"I cannot imagine. I cannot imagine. ... There's no reason for anyone to have done something like this," Winston said.
Crutcher, who was the father of the 3-year-old, was found dead in the Alabama woods, just across the Tennessee state line, police said. They did not reveal the cause of death for him, the women or the dead child.
Helm said Crutcher had former or current relationships with Campbell and McCaulley and authorities have been told he was living at least some of the time with Brown.
The sixth victim, Jeffrey Pope, also knew Crutcher. He died of a gunshot wound to the chest in Huntsville, Madison County, Ala., Coroner Craig Whisenant said.
Crutcher was out of jail on burglary and assault charges in Limestone County, Ala., when he died.
According to Alabama court records, Crutcher was released on $15,000 bond on Oct. 4 on charges that he and four other men broke into a home and assaulted a man to collect a drug debt. He was scheduled to appear in court Nov. 20 for an arraignment.
The Tennessee Department of Children's Services had no prior involvement with Campbell, Crutcher or the children, spokeswoman Molly Sudderth said Tuesday. She said the slayings would lead DCS to open a case and, if needed, take the 3-year-old into state custody until permanent arrangements could be made for him.
Associated Press writer Bob Johnson contributed to this story from Montgomery