Decades of alcohol abuse and living on the streets took a severe toll on the body of a Newport Beach homeless man found dead earlier this year, an Orange County Sheriff-Coroner report shows.

Mark David Allen, 50, had an enlarged heart, liver disease and showed signs from past medical issues when he died in the early hours of Feb. 1 at 43rd Street and Seashore Drive in Newport Beach.

His cause of death was listed as heart disease.

"He died kind of like a 70- or 80-year-old man in his sleep, but he did it 20 or 30 years earlier because of what alcohol did to his system," said David Sperling, a custody officer with Newport Beach police who documented Allen's years of arrests and alcohol abuse.

Allen grew up in Newport and remained a fixture in the community until his death. Sperling recorded Allen's slide into the depths of alcoholism in the award-winning documentary "Drunk in Public," which tracked the surfer's hundreds of arrests over more than 15 years in Southern California and a brief stint in Hawaii.

A toxicology report showed that Allen had no drugs or alcohol in his body when he died.

Allen was known to have a seizure after as few as six hours without alcohol, Sperling said, adding that he was as predictable medicalwise as any arrestee he has seen.

"The reality is, he died totally sober yet he didn't have any withdrawal issues," Sperling said. "It's totally fascinating."

Officers were talking with Allen hours before his death and reported that he was sober and in a good mood, bellowing out songs as he was known to do, Sperling said.

After his death, locals remembered Allen as, at times, affable or belligerent. But to thousands of rehab workers and addicts across the country who saw "Drunk in Public" but never met him personally, Allen was a cautionary tale.

joseph.serna@latimes.com

Twitter: @JosephSerna