Previous police reports suggested Adolphus Earl Kimrey II, who has been charged with her murder, used chloroform, - a liquid used as a general anesthetic - to kill Mariah before dumping her body in Pender County's Shelter Creek.
Kimrey was Wood's mother's boyfriend at the time of her death.
The autopsy also detailed traumatic head injuries Mariah sustained.
Mariah was last seen in bed by her mother around 11 p.m. on November 26. Her disappearance prompted an Amber Alert on November 27 that gained national attention.
In addition to murder, records show Kimrey was also charged with felony child abuse resulting in serious bodily injury/death.
RELATED: Mother's boyfriend charged w/ murder in Mariah Woods' death
Kimrey was initially being held on several other charges including concealing an unattended death.