Lawyers for the girl's estate say there was a systematic failure that led to her death.
The suit claims Malinda Hoagland was failed at many levels of government, including the school district and county child services.
READ MORE: Father and stepmother charged with murder of girl, 12, who was abused, tortured and starved: DA
Father and stepmother charged with murder of girl, 12, who was abused, tortured and starved: DA
Authorities allege her father, Rendell Hoagland, and his girlfriend, Cindy Warren, tormented and beat the girl.
Authorities also said some of the horrific abuse was captured on surveillance cameras inside the couple's Chester County home.
"Starved, abused and completely humiliated," said attorney Tom Bosworth. "Shackled to furniture naked, with metal things that should really only be in prisons."
Bosworth represents Malinda's adult half-sisters who are suing Chester County Children, Youth and Families, the Coatesville Area School District and other government agencies.
Bosworth said staff at North Brandywine Middle School called the state ChildLine with concerns about her habitual absences and possible abuse but says child services dropped the ball.
Bosworth said the agency only placed a call, and Malinda Hoagland's father and his girlfriend told officials the girl was fine.
"Not one time did county officials go visit the home," he said. "Not one time did they interview Malinda. Not one time did they speak with this child."
Still, he said the schools should've done more with what he called continued evidence of abuse.
A Chester County spokesperson had no comment.
The Coatesville Area School District released a statement back in May that read in part: "The school had concerns about the child's welfare in the fall and diligently reported those concerns to Children and Youth Services and shortly thereafter the child was withdrawn and enrolled in a cyber charter school."
The family said the 12-year-old who weighed just 50 pounds was one of many signs missed by those who were supposed to protect her.
Bosworth said county officials knew Malinda was living with a convicted child abuser. In 2009, Warren was sentenced to 3-7 years in prison for endangering the welfare of her son.
Malinda Hoagland's estate hopes the lawsuit will spur a national registry of child abusers much like Megan's Law.
"What they want out of this is change," said attorney Alexandria Crouthamel. "They are not looking for damages, they could care less if it's $1 or a billion dollars. What they are looking for is change."
Rendell Hoagland and Cindy Warren remain behind bars, charged with murder. The Chester County DA says he'll seek the death penalty.