Robert Durst hacked an animal to pieces while dressed as a woman! That shocking claim comes from a new book authored by William Steel, a longtime associate of Durst, who’s now infamous as the septuagenarian heir to a New York real-estate fortune. The filthy-rich man is accused of multiple murders, including currently being tried in L.A. for killing his friend Susan Berman in 2000! In “Sex and the Serial Killer: My Bizarre Times with Robert Durst,” Steel claimed the millionaire spent time in his New York apartment with a prostitute in the ’80s. Steel wrote that he returned to the apartment one day and found Durst “sitting on the bed in his green dress, covered in blood. He was holding a knife in his right hand and had a broad maniacal smile of satisfaction on his face.” Read on for details of Steel’s shocking claims, and click here for more true-crime news ….