Dean Martin was a victim of both his profession and his generation, as 50 years in the spotlight – starting in the 1940s – took its toll on the late entertainer.

On Christmas Day 1995, the "King of Cool" died at the age of 78, leaving behind a legacy in music, movies and television.

But Martin was famous for other things, too; for example, he was rarely seen not smoking a cigarette.

His lifelong habit eventually led to emphysema and later lung cancer, but that alone didn't kill him.

Martin's alcohol consumption – which morphed into more than just trying to keep up his "drunk" stage persona – escalated exponentially in the last eight years of his life, and he eventually became dependent on opioids.

"Dean Martin's death certificate states respiratory arrest as the cause of death," explains medical examiner and forensic pathologist Dr. Michael Hunter. "It appears that after he was diagnosed with emphysema, he continued to smoke heavily, which further damages the lungs and worsens the disease."

"But his death certificate also lists heart failure as a contributing factor," adds the expert. "Throughout his life, Dean had a reputation as a legendary drinker. Alcohol is well-known to increase blood pressure, which weakens the heart muscle. So I want to investigate whether this is, in fact, the key to why he died."

Unfortunately, drinking and smoking simply came with the territory of working the bar, club and casino scene where Dean Martin started out, and he took those habits with him everywhere he went.

Soon enough, Martin shot to international stardom as a singer. He released more than 30 albums and even knocked The Beatles out of the top spot on the charts with his hit, Everybody Loves Somebody.