A North Carolina toddler found dead in December was killed with chloroform, according to a preliminary autopsy. Three-year-old Mariah Woods’ cause of death was determined to be chloroform toxicity, the Onslow County Sheriff’s Office said in a statement Wednesday.

Chloroform is a colorless liquid used as an anesthetic, though when used in large doses can supress both the nervous system and respiratory system.

“We suspect this chemical was used to disable the child,” said Onslow County Sheriff Hans Miller, according to WRAL-TV. “And according to the autopsy report, it led to her death, which is real unfortunate, as we all know.”

Mariah’s mother reported her missing in November after she awoke to discover the girl was not in their home. Her body was found in a nearby creek after a five day search.

Adolphus Earl Kimrey, Mariah’s mother’s live-in boyfriend, was charged Wednesday with first-degree-murder in Mariah’s death. He was previously arrested after the toddler disappeared and charged with concealing her death, second degree burglary, felony larceny and possession of stolen property and obstruction of justice. It was unclear whether he had entered a plea for the new charges.

“These additional charges do not mean the investigation is concluded,” the Sheriff’s Office said. “But [we] will continue until all leads and information is thoroughly evaluated.”

Kristy Woods was cooperating with the investigation and had not been charged in relation to her daughter’s death, authorities said. Kimrey was expected to appear in court again Feb. 14.

“The death of a child is always a sobering reminder of how fragile life is,” said Miller. “When the community is so deeply affected by such a horrific crime it is sometimes difficult to not allow our emotions to influence the decisions that we make. However, the best way to honor Mariah is to ensure a fair and thorough investigation, which will lead to a successful prosecution. We must remember that through these moments, together, as a community, we can ensure that justice will be delivered to Mariah. We sincerely thank the community for their patience and support through this entire investigation.”

Mariah Woods Mariah Woods, a North Carolina toddler found dead in December, was killed with chloroform.