"Playboy" founder Hugh Hefner died of a severe strain of E. coli and a blood infection in addition to going into cardiac arrest, according to a death certificate obtained by The Blast.

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Cardiac arrest is listed as the first cause of death, followed by respiratory failure, septicemia, a severe blood infection, and E. coli “highly resistant to antibiotics.”

Hefner died at age 91 Sept. 27 at his Playboy Mansion surrounded by his wife, Crystal, and children.

According to the Los Angeles Times, he was laid to rest Saturday in the private ceremony at Westwood Village Memorial Park Cemetery. He is next to Marilyn Monroe, the first cover star of "Playboy."

Hugh Hefner pictured in 2013.

Credit: Charley Gallay/Getty Images for Playboy

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Credit: Charley Gallay/Getty Images for Playboy