An autopsy report released confirms the death of Isabel Celis as a homicide, but it was not able to explain how she died.
Investigators found a portion of Isabel Celis' skull, and not much else when they identified her remains earlier this year.
The six-year-old girl disappeared from her family home in April 2012.
Her disappearance and massive multi-agency search made national headlines. Thousands of leads turned up nothing.
The National Center for Missing and Exploited Children released an age progression of Isabel Celis in hopes of sparking new leads a few years later.
Five years later investigators recovered some of her bones.
A portion of the child's skull and a small part of her pelvis were found among non-human bones.
The location where her remains were found is redacted in the report obtained by KGUN 9.
The remains were so limited, the Pima County Medical Examiner's Office could not match them to Isabel Celis based on the bones and dental records alone.
A firm match required DNA analysis.