This story discusses suicide. If you or someone you know is having thoughts of suicide, please contact the Suicide & Crisis Lifeline at 988 or 1-800-273-TALK (8255).

"The Young and The Restless" star Billy Miller's cause of death was determined to be due to a "gunshot wound of head," according to documents obtained by Fox News Digital.

The Travis County Medical Examiner in Austin, Texas, ruled Miller's manner of death as "suicide."

Miller died Sept. 15 in Austin. He was 43.

BILLY MILLER, TV SOAP STAR, DEAD AT 43

"Emergency medical services responded and he was pronounced dead at the scene," according to the autopsy report. "Multiple letters indicating suicidal intent and instructions for others were found at the scene."

A postmortem toxicology exam discovered trace amounts of "ethanol, cocaine and its metabolites, diphenhydramine, and amphetamine." Diphenhydramine is more commonly known as an antihistamine medication to relieve symptoms from allergies, while amphetamines are stimulants.

Miller's representative confirmed to Fox News Digital at the time that Miller was "struggling with manic depression when he died."

‘THE YOUNG AND THE RESTLESS’ STAR BILLY MILLER'S MOTHER SETS THE RECORD STRAIGHT ABOUT HIS CAUSE OF DEATH

Shortly after leaving his role as Richie Novak on ABC's "All My Children," Miller landed the role of Billy Abbott on CBS' "The Young and the Restless," where he earned three daytime Emmy Awards.

The actor also portrayed Jason Morgan/Drew Cain for six years on the ABC soap opera "General Hospital."

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In addition to his daytime television credits, Miller was also known for his work on "Ray Donovan," "Justified," "Ringer" and "American Sniper," and starred on a handful of episodes of Meghan Markle's show "Suits." He also portrayed Alex Dunn on the AppleTV+ show "Truth Be Told" with Octavia Spencer and the late Ron Cephas Jones.

Miller was born in Tulsa, Oklahoma, and raised in Grand Prairie, Texas. After graduating from the University of Texas, Austin, he moved to Los Angeles and "began working in the mailroom of a prominent entertainment management/production company," his rep said. 

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Miller pursued a career as an actor only after "encouragement (a dare) from friends," and his first successes came in the commercial world, where he quickly booked multiple national ads.

He also was a restaurateur and owned several bars and restaurants in the Los Angeles area for many years.

"He is survived by his mother Patricia, sister Megan, brother-in-law Ronnie, nephew Grayson and niece Charley," his representatives said in a statement. 

"He also leaves behind a great many friends and colleagues who will miss his warm personality, generous spirit, and genuine kindness."