Timothy Burns, 42, was charged with arson and two counts of murder in the deaths of Jaidon Hill and his mother, Atira Hill, whose bodies were found Tuesday in a wooded area, along with the body of Jaidon's stepfather, Laterry Smith.
Copiah County Sheriff Harold Jones said Burns -- who had led investigators to the bodies -- was not immediately charged with killing Smith because investigators were not sure which county Smith was killed in, CNN reported.
The victims were last seen alive Friday in a car that was later found overturned and burning.
Jones said investigators think Burns was driving the car and became involved in a crash before setting it on fire, and they do not think he knew the victims.
"We don't think there is [a relationship]," Jones said. "But we haven't tied that loose end up yet."
Burns wore protective body armor when he was taken to court for a hearing Wednesday.