() The junior coroner who performed the autopsy of Marilyn Monroe still has his doubts over the circumstances of her death, 63 years on.

Monroe died Aug. 4, 1962, at the age of 36. Evidence has long pointed to suicide, but some have their doubts.

Coroner Thomas Noguchi, 98, performed the autopsy and told author Anne Soon Choi, in her book L.A. Coroner, he felt “alarm bells going off on his head” when the head toxicologist refused to run additional tests.

Choi said “a wave of anxiety” washed over Noguchi, via the Daily Mail. According to the author, he was never able to fully free himself from doubts over what really may have happened to Monroe.

Following Monroe’s death, the public was told Monroe died at her own hand via the ingestion of sleeping pills.

“When he does the evisceration of her body, that’s the removal of the organs; he found nothing in her stomach, and there’s no corollary between that relative to the ingestion of pills and what you’re going to get back on the toxicology report,” forensic analyst Joseph Scott Morgan told “Banfield.”

“Because her levels were blown through the roof. As a matter of fact, they’re described in terms of being lethal levels. And it’s kind of a fascinating dynamic. How are the drugs delivered into her system?”

Morgan made mention of speculation that Monroe may not have killed herself and instead administered a lethal suppository, given there were no injection marks found on her body.

“My suspicion is that Marilyn Monroe’s death will forever remain shrouded in mystery and plus, it’s great talk for people to continue on about for years and years after the fact,” he added.