In July 2010, Teghan Skiba was admitted to the Johnston Medical Center by then-21-year-old Jonathan Richardson after he claimed she had fallen off the bed. However, doctors found she had cuts, bruises, and bite marks on her body.
Skiba died days later. An autopsy revealed that the girl died from a blow to the head.
Richardson was charged with first-degree murder, and felony child abuse inflicting serious bodily injury.
He's also accused of beating and sexually assaulting the girl for 10 days while her mother, Helen Roxanne Reyes, was out-of-state for Army Reserves training.
"Deliberate, repeated acts of sadistic abuse, repeated acts of sadistic abuse not only physical but sexual, not only for the purpose of discipline, but sadistic pleasure," Prosecutor Paul Jackson said during opening statements Monday.
The Johnston County Sheriff's Office and prosecutors have said Reyes knew the girl was being abused and later indicted her on charges of felony child abuse.
Authorities said the couple was living with Skiba in an air conditioned barn behind the home of Richardson's grandparents on the outskirts of Smithfield near Brogden. There was no running water, no bathroom, and just a single air mattress on the floor to sleep on.
The defense contends Teghan's death was an accident, and that Richardson really loved the girl.
Reyes has been free on bond since her 2010 arrest. She is still awaiting trial.
Meanwhile, prosecutors are seeking the death penalty against Richardson.