Audrii Cunningham's cause of death revealed: Abducted Texas girl, 11, was found tied to rock on river bed as cops charge dad's swastika-tattooed babysitter friend

Audrii Cunningham's cause of death has been revealed after the body was found in a lake tied to a rock with a rope that matched one found in the car of a family friend accused of her murder.

She was found to have died from blunt force trauma. The death has been ruled a homicide following the autopsy. 

Don Steven McDougal, a Nazi tattooed family friend who authorities say was supposed to be taking Audrii to the school bus stop the day she vanished, has been charged with the 11-year-old's murder. 

He was already under police custody in connection with an unrelated assault in Livingston, Texas.

An Amber Alert was issued for the girl after she did not board the school bus on February 15 and was absent from school. She was last seen at around 7am near her home in Livingston.

Her body was discovered in a river on Tuesday with a 'large rock' tied to her body after police used cell phone records, video analysis and information from McDougal to find her.

'The rope used was consistent with rope that was observed in McDougal's vehicle on a traffic stop two days prior,' the criminal complaint against McDougal states, as reported by CNN.

Audrii Cunningham's body was found in a lake tied to a rock with a rope that matched one found in the car of a family friend accused of her murder. Audrii was found to have died from blunt force trauma. The death has been ruled a homicide following the autopsy

Don Steven McDougal, a Nazi tattooed career criminal who lives on her father's property in a trailer, has been charged with the 11-year-old's murder

Audrii's father, Joshua, pictured with the man accused of killing his daughter, Don Steven McDougal. The suspect's swastika and SS tattoos are clearly visible on his left arm

Police say the girl's body was recovered on Tuesday from Trinity River after they used cell phone records, video analysis and information from McDougal to find her

The alleged killer had taken the girl to the bus stop in the past or would take her to school if she missed the bus, officials said.

After she was reported missing, investigators discovered she had not boarded the bus to go to school on the morning that she disappeared. 

A Hello Kitty backpack that authorities believe belonged to the child was then found on Friday near the dam on Lake Livingston, one of the state's largest lakes.

McDougal, who has a criminal record spanning back to the early 2000s, had joined the search efforts and was seen knocking on neighbor's doors while asking if anyone had seen Audrii. 

He claimed on social media he had 'done nothing wrong,' as reported by CNN.

'I have done everything I can to help find her. I have done nothing wrong,' he wrote in a comment on a Facebook page.

Audrii's family had reported her missing on Thursday after she failed to return after school to her home in Livingston

A mugshot of McDougal, the last person to see the youngster alive, according to police  

Audrii's body was found on Tuesday in the Trinity River near US-59, Polk County Sheriff Byron Lyons announced. 'My heart aches with this news and I express with my deepest sympathy and condolences to everyone who knew, who cared for, and loved Audrii,' Lyons said

The sheriff also said that the Trinity River Authority lowered water levels on the river, which led to the discovery of her body

McDougal had allegedly walked Audrii to school on the morning she vanished 

As authorities investigated Audrii's disappearance, they had named McDougal as a person of interest and he was arrested last Friday on an unrelated assault charge.

Prosecutors have said there is 'substantial evidence' in the case, and that cell phone data and videos helped identify places to search. Officials added that the Trinity River Authority lowered water levels on the river, which led to the discovery of her body.

Court records from Brazoria County, south of Houston, show McDougal pleaded no contest to two felony counts of enticing a child stemming from a 2007 incident and was sentenced to two years in prison. 

The sheriff said that the girl's body has been taken to the Harris County medical examiner's office in Houston to determine the cause of death.

Audrii lived with her father, grandparents and other family members, authorities said. 

McDougal has a criminal history dating back to 2001 that includes convictions on two counts of enticement of a child

Audrii sparked a state-wide search after she vanished early Thursday morning in Livington, around an hour north of Houston 

As authorities investigated Audrii's disappearance last week, they had named McDougal as a person of interest and he was arrested last Friday on an unrelated assault charge 

When the search was still ongoing, the girl's mother pleaded for help from the public and said it was not like her daughter to just run off or disappear. 

'We have no leads so we are grasping at any string, any signs, anything in general,' she told KPRC at the time. 

'There is not one feeling you feel,' she said. 

'You are broken, you are mad, you are empty and right now I am empty. 

'I am not going to be the same unless my baby is returned to me and neither is her family, any of us, any of her friends, any of the people that she has been connected to in the community.'