Sonny Liston, heavyweight boxing champion in the early 1960s, died near the beginning of 1971. The reason listed on the death certificate: natural causes. But nearly 50 years later, the question of whether he was murdered is an open one for some. It’s a question Shaun Assael set out to answer with his book, The Murder of Sonny Liston: Las Vegas, Heroin, and Heavyweights.