— The adoptive mother of Erica Parsons pleaded guilty Friday to repeatedly abusing and eventually killing the Rowan County teen.

Casey Parsons, 44, will spend the rest of her life in prison for first-degree murder and felony child abuse.

"In the end, I failed her by choosing one child over another child," Parsons said in court. "I want to say I'm sorry to God and to Erica."

Erica Parsons was reported missing on July 30, 2013. Her brother said she hadn't been seen since November 2011, but Casey Parsons and her husband, Sandy Parsons, maintained she was living with a relative in Asheville.

When that relative couldn't be found, authorities turned their attention to Casey and Sandy Parsons, who were convicted in 2014 on federal charges of fraudulently accepting adoptive care benefits for Erica when she was not living with them.

Two years after that, Sandy Parsons led investigators to Erica's remains in a shallow grave in Chesterfield County, S.C.

Family members reported that Erica was subjected to physical and emotional abuse by her adoptive parents, including that they forced her to sleep in a closet and eat dog food and would choke her and throw her to the ground.

Prosecutors provided horrifying details of the abuse during Friday's court hearing as Casey Parsons sat nearby and showed no emotion as she listened.

Sandy Parsons is also charged in the girl's murder. He is expected to stand trial on those charges.