A man whose body was found in the wheel well of a United Airlines jetliner at San Francisco International Airport on July 19 died from a lack of oxygen, the San Mateo County coroner's office said on July 20.

The man, who appeared to be Asian and in his 50s, died five to ten minutes after take off as the Boeing 747 ascended and the air got thinner, said San Mateo County Coroner Robert Foucrault. Foucrault said the man, who has not been identified, also had a broken right thighbone, which probably occurred as the landing gear retracted.

The body was found in the nose gear wheel of the plane during a routine inspection after a flight from Shanghai. The man wore eight layers of clothing, Foucrault said.

He said authorities are working to identify the man.