Tom Petty’s Cause of Death Remains a Mystery as His Death Certificate Is Released

The cause of Tom Petty‘s sudden death is still a mystery.

The rock icon was 66 when he died on Oct. 2 after suffering a cardiac arrest, but his death certificate — obtained by TMZ —  lists the immediate cause of death as “deferred.” The outlet notes that not identifying the official cause of death could mean officials are still waiting for autopsy results.

The Los Angeles County coroner’s office completed an autopsy on the late singer, but the cause of death will require further examination, department spokesman Ed Winter told the Associated Press. The outlet reported Petty had not seen a doctor in six months, no foul play is expected and toxicology results may take weeks to surface.

Petty’s death certificate listed him as a songwriter and musician who worked in the field for 40 years and had lived in Malibu for 43 years. His wife, Dana Marie York, was also listed.

Petty’s longtime manager released a statement to PEOPLE last Monday saying, “On behalf of the Tom Petty family we are devastated to announce the untimely death of our father, husband, brother, leader and friend Tom Petty. He suffered cardiac arrest at his home in Malibu in the early hours of this morning and was taken to UCLA Medical Center but could not be revived. He died peacefully at 8:40 p.m. PT surrounded by family, his bandmates and friends.”

Petty was found unconscious and not breathing in his Malibu home after suffering a full cardiac arrest, TMZ reported. Law enforcement officials told the outlet that the rock legend was rushed to UCLA Santa Monica Hospital where he was put on life support and his pulse returned. Later the decision was reportedly made to remove him from life support after it was found that he was lacking brain activity.

In honor the 40th anniversary of Tom Petty and The Heartbreakers, Petty and the band hit the road for a cross-country tour, which started in April and ended just one week before his death.