The autopsy was performed Tuesday by Teton County Coroner Dr. Brent Blue.
In a tweet, Dr. Blue ruled the death a homicide but said the cause of death is pending final results.
The news comes as authorities are continuing their search for Petito’s fiancé, Brain Laundrie, who is a person of interest in the case.
Authorities have been searching the Carlton Reserve in Florida, which is where Laundrie’s family said he went for a hike a week ago…and never returned.
The Florida police said that Petito’s case is now officially a “criminal investigation.”