A 10-year-old girl who vanished on a walk with the son of her dad’s girlfriend was beaten to death, according to an autopsy report.

Authorities released the details of an autopsy on Kiaya Campbell whose body was discovered in June in a wooded area of Thorton, Colorado, news station KUSA reported.

Two days after she was found dead, police arrested the 15-year-old boy she was last with before she disappeared, news station KBZK reported. The suspect was later identified as Aidan Zellmer.

Zellmer was charged with first-degree murder in connection to her death.

He told police that he got separated from the 10-year-old during a rainstorm.

Campbell’s autopsy report, which was obtained by KUSA, revealed that she had suffered a number of horrific injuries.

There were signs of blunt force trauma to her head, which caused skull fractures.

The report said there were also open lacerations on her head, among other bruises on her body.

Police have not released a possible motive for her death.