De Villota, 33, was found dead in a hotel room in Seville, Spain on Friday. "I can confirm that her death was due to natural causes. The family has been informed," Dr Joaquin Lucena Romero, head of forensic services at the Institute for Legal Medicine, said.
Spaniard De Villota lost her right eye in a crash in July 2012 while testing for the Marussia team.
She suffered severe head and facial injuries after colliding with a lorry at Duxford Aerodrome, Cambridgeshire, but had been cleared to resume driving.