Adopted girl, 13, found dead wearing just a diaper in unimaginable house of horrors

A former Florida Department of Children and Families employee has been arrested for allegedly abusing her 13-year-old adopted daughter, who was found dead wearing just a diaper.

Diane Natasha Mack, 34, who once worked as a guardian ad litem - a person appointed by the courts system to represent the interests of someone who is unable to care for themselves - called police to her home in the Sun 'n Lake of Sebring golf and recreation community on Friday at 12.19am to report her adopted daughter dead after finding her 'lying unresponsive' on the floor. 

When deputies arrived at the scene, they found the unidentified victim dead next to the front door, wearing nothing but a diaper and showing 'clear' signs of abuse and neglect, the Highlands County Sheriff's Office reports.

'She was extremely emaciated and obviously malnourished,' Sheriff Paul Blackman said. 'Her body was covered in wounds in all stages of healing, including lacerations that were clearly recently suffered.'

The sheriff went on to call the crime scene 'one of the most disturbing ... I have encountered in more than 30 years of law enforcement.'

'There are no words I can say that can truly convey the nightmare that this child's life must have been.'

Authorities now claim that Mack initially told officers on the scene she found the girl on Thursday morning - but later changed her time of discovery to around 3pm.

Further investigation also uncovered evidence suggesting the girl, who was homeschooled, had been locked up in a garage, the sheriff's department said.

It is unclear how long the girl had been kept inside the garage, officials said, but 'it appears she was secured to the garage door and monitored from inside the home by a security camera that had been mounted in the garage,' officials said.

Deputies also claim Mack left her daughter 'lying dead on the floor,' while she used 'pool chlorine' to try to destroy evidence inside the garage.

She also allegedly took the time to drive at least four other children who were living inside the home with her to another residence in Titusville, before she returned to Sebring to report the girl's death. 

Mack is now being held without bail at the Highlands County Jail as she faces charges of first-degree murder while engaged in aggravated child abuse, aggravated child abuse, kidnapping and destroying evidence.

Sheriff Blackman, meanwhile, has insisted the department 'will do everything in our power to make sure that there is justice for this child.'

'Parents have a duty to love our children and make sure no harm comes this way,' he said. 'To see a child treated this way is not only heartbreaking, it's infuriating.

'What makes it even more appalling is that the suspect is a former employee of not only the Department of Children and Families, but also worked as a guardian ad litem. 

'That someone whose job it was to look after the welfare of children could treat their own child in this manner is simply beyond belief.'