George Kennedy, who won an Oscar for Best Supporting Actor in “Cool Hand Luke,” died Sunday, a spokesman for the Canyon County, Idaho coroner’s office told TheWrap on Monday. He was 91.

According to the coroner’s office, Kennedy died Sunday at 4:30 a.m. at a care facility in Middleton, Idaho.

The coroner spokesman said that Kennedy died from a heart-condition, adding that he believed that the condition was long-term.

Kennedy’s grandson Cory Schenkel told TMZ that Kennedy had been in failing health since the death of his wife Joan slightly more than a year ago, and had been in hospice care for a month.

Kennedy’s film credits also included “The Dirty Dozen,” the “Airport” movies, a series of “Naked Gun” comedies and the disaster film “Earthquake,” among many others.

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Kennedy also starred as rival rancher Carter McKay in the long-running CBS drama “Dallas” for three seasons. His many television appearances included roles on “The Andy Griffith Show,” “Peter Gunn,” “Bonanza,” “Maverick,” “McHale’s Navy” and “Gunsmoke.”

As an author, Kennedy wrote three books, including the 1983 murder mystery “Murder on Location,” the novel “Murder on High,” published the following year, and his 2011 autobiography, “Trust Me.”

The actor, who was born in New York City in 1925, began as a radio performer but set his entertainment career aside during World War II, serving with the U.S. Army for 16 years.

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Kennedy launched his acting career after receiving encouragement from Phil Silvers, on whose television show Kennedy served as a technical adviser.

Kennedy’s last major acting role was in the 2014 Mark Wahlberg film “The Gambler.”