The Clark County Coroner and Medical Examiner's office in Nevada has completed its investigation, issuing a statement overnight.
"The Coroner's Office has determined that Mr McCarthy died on September 9, 2012 (at) 6.16am, from multiple injuries due to a fall from height from a roof," the statement said.
"The manner of death has been ruled accidental."
The statement included no word on the results of toxicology tests.
"The toxicology reports are not public information in this case because toxicology isn't considered to be a direct cause of death. The cause was accidental, due to injuries as a result of the fall," a Clark County spokesperson told AFL.com.au.
McCarthy, 22, was on an end of season trip with Port Adelaide teammates when he became separated from the group.
He fell to his death from a mezzanine roof of the Flamingo Hotel and Casino on the famous Las Vegas strip.
Hundreds attended the former Collingwood player's funeral service in Sorrento during preliminary final week, including mates from both the Magpies and Power.
