Lisa Marie Presley's cause of death still not revealed?

Lisa Marie Presley's sudden death has sent shockwaves into the media industry. However, the star's cause of death is still unknown.

According to RadarOnline, the autopsy of the 54-year-old was carried out on January 14. But the toxicology reports are still pending as the Los Angeles County Coroner's Office has not received the results yet.

Michael Jackson's former wife was rushed to the hospital after she had a cardiac arrest and passed away.

"It is with a heavy heart that I must share the devastating news that my beautiful daughter Lisa Marie has left us," her mother, 77-year-old Priscilla Presley said in a statement at the time."She was the most passionate, strong, and loving woman I have ever known.

"We ask for privacy as we try to deal with this profound loss. Thank you for your love and prayers."

Presley left with three children with her estranged former husband, Michael Lockwood.