Smithfield, N.C. — The mother of a 4-year-old girl who authorities say died after being tortured was charged Thursday with negligent child abuse.

Teghan Skiba died July 19 at UNC Hospitals in Chapel Hill, three days after she had been taken to a Smithfield hospital. She had cuts, lacerations, bite marks, head trauma and sexual assault injuries, authorities said.

Jonathan Douglas Richardson, 21, of 750 Old Sanders Road in Smithfield, is charged with first-degree murder and child abuse in connection with her death.

Teghan and her mother, Helen Reyes, had been living with Richardson in a barn on his grandparents' property for four weeks before she left her daughter in his care on July 6 to go to New Mexico for military training.

A Johnston County magistrate set a $50,000 bond for Reyes, 26, whose address is listed on the arrest warrant as 5255 Passenger Place in Raleigh. She remained in jail Thursday evening.

"She neglected to carry out her motherly duties," Johnston County Sheriff Steve Bizzell said, calling the case the worst child abuse he and his investigators have ever seen.

The arrest warrant alleges that the physical abuse, which included forcing Teghan to consume alcohol, started before Reyes left town, but she still chose to leave the girl with Richardson.

"She had witnessed her child being beaten at the hands of Jonathan Richardson before she left, so yes, she (was) a lot to blame for this," Bizzell said. "Children are helpless. We have a so-called mother that just walked away."

In a Wake County Human Services investigative report released Wednesday, social workers determined Reyes had failed "to protect her child and to entrust her child to an appropriate caretaker."

"The finding concerning Ms. Reyes does not mean that she personally inflicted injuries on Teghan," the report stated. "The definition of abuse in (state law) includes creating or allowing to be created a substantial risk of serious physical injury by other than accidental means."

Richardson initially told hospital workers that Teghan had fallen off the bed. He later told Johnston County investigators that he "lost it" and whipped the girl with a cord after she went to the bathroom in the bed they were sharing, according to search warrants. He explained that he is "bipolar and little things set him off."

The report noted that Wake County social workers never received any reports of suspected abuse or neglect of Teghan and that Johnston County Child Protective Services never investigated the case because that agency didn't know the girl was living in Smithfield.