Prince's Autopsy Completed ... Still No Cause of Death

12:54 PM PST -- The coroner's office just released Prince's body to his family.

Prince's autopsy was just completed ... but the cause of the singer's death is still a mystery.

The four hour procedure started at 9 AM CDT Friday and Prince's body will be released to his family later today. We're told results from the exam won't be disclosed until toxicology results come back ... which could take several weeks.

A rep for the Midwest Medical Examiner's Office in Minnesota says they're still collecting the singer's medical records as well as family medical history to complete their investigation.

As TMZ reported, Prince was spotted Wednesday pacing outside a local Walgreens waiting on a prescription.