LOS ANGELES (AP) -- Carrie Fisher's death certificate confirms that the actress died of a heart attack, but it says more investigation is needed to try to determine the underlying cause.
The Los Angeles County death certificate was obtained Monday by The Associated Press.
Under "cause of death" it says "cardiac arrest/deferred." The "deferred" designation indicates that more investigation is needed, usually in the form of toxicology tests that can take several weeks to complete.
Fisher had the heart attack on a flight from London to Los Angeles on Dec. 23. She died at age 60 on Dec. 27 at Ronald Reagan UCLA Medical Center, the certificate says.
Her mother Debbie Reynolds died a day later.
The death certificate lists Fisher's daughter Billie Lourd as the notifying party, and gives Fisher's occupation as "writer."