On Monday, Tennessee officials found three women and an 18-month-old boy dead at two different homes in Lincoln County, about 100 miles south of Nashville.
A body found Tuesday in Alabama may be Warren Vincent Crutcher, who was sought for questioning by Tennessee investigators, Madison County Coroner Craig Whisenant said.
Lincoln County Sheriff Murray Blackwelder said two children survived the attacks, and he identified one of them as Crutcher's 3-year-old son.
Whisenant said authorities haven't positively identified the dead man in Alabama. He wouldn't comment on the cause of death but said it wasn't suicide.
The investigation started in Tennessee on Monday morning, Blackwelder said.
The 3-year-old boy, identified as Vincent Crutcher, called relatives saying he couldn't wake up anyone at his house, his godmother, Constance Winston, told WAFF-TV in Huntsville.
Family went to the house and found all 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 arrived at his home outside Fayetteville, they found his mother, 22-year-old Chabreya Campbell, and her 18-month-old son Rico Ragland dead. The body of 21-year-old Amber McCaulley of Huntsville, Ala., was also inside the home.
"I cannot imagine. I cannot imagine so it has to be something that's totally off the realm because there's no reason for anyone to have done something like this," Winston said.
Hours later, the body of 21-year-old Jessica Brown was found in her home in Fayetteville, Tenn. Her 2-month-old child was found in the home unharmed.
The cause of death hasn't been released and the bodies were sent for autopsies.
Tennessee authorities identified the elder Crutcher as a person of interest, said he was likely armed and alerted Alabama officials to watch for him.
The body in Alabama was found in woods by utility crews, WAFF reported.
Blackwelder said Tuesday that he doesn't think there are more victims in Tennessee.
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.