Helen Reyes boyfriend - 21-year-old Jonathan Douglas Richardson - was charged last week with first-degree murder in the death of Teghan Alyssa Skiba.
Now, the Johnston County Sheriff's Office and prosecutors say Reyes knew the girl was being abused.
"She knew he had beaten the little four year old girl in her presence before," Johnston County Sheriff Steve Bizzell told ABC11.
According to new search warrants, Skiba was a victim of "forced consumption of alcohol". The warrants state that she suffered severe physical beatings and assault by biting between July 5 and July 16. The warrant says Reyes had "firsthand knowledge" of this kind of abuse before July 5.
"This is the worst case of torture of a child and child abuse and neglect that we've ever seen," said Bizzell.
Deputies say Richardson took the girl to the Johnston Medical Center July 16 claiming she fell out of bed. But doctors called authorities when they discovered human bite marks, bruises, cuts, severe head trauma and evidence of extreme sexual abuse.
Richardson was supposed to be caring for the child while Reyes attended military training with the Army National Guard in New Mexico
According to search warrants, Richardson shared the same air mattress with the girl in an outbuilding behind Richardson's grandparent's house on the outskirts of Smithfield near Brogden. There was no running water and no bathroom.
Search warrants state Richardson told detectives he "lost it" when the little girl urinated and defecated in their shared bed.
He said he whipped her with an electrical cord.
He also stated he was bipolar and 'little things set him off."
Reyes was set to have her first court appearance Friday. Bond was set at $50,000. Richardson is being held without bond in Johnston County Jail.