Kaiden Demus' body was found just after 9:30 a.m. Monday inside a home in the 2700 block of Edwards Avenue in Spring Lake.
Officers went to the house after a 911 call came in from someone reporting the child was unresponsive - possibly due to a drowning.
However, officials said an autopsy later determined that Demus died as the result of blunt force trauma to the head.
Cumberland County Sheriff's detectives are continuing to investigate.
Further details about the incident have not been released.