Robert Durst, the subject of HBO's fascinating documentary series The Jinx, sought protection from a Philly biker gang called the Kensington Gang Bangers while serving a short stint in prison, according to an article on Vice.
Durst spent time in FCI Fairton, located in New Jersey about an hour outside of Philadelphia. Durst spent five and a half months there for bond jumping and evidence tampering related to the shooting death of his 71-year-old neighbor Morris Black.
Writer Seth Ferranti spent time in Fairton with Durst. He writes that a Kensington gang took interest in Durst, perhaps because he was paying them protection money. Ferranti writes:
"Snake and Joker* used to look out for him," my friend says. "There was an incident where a Spanish guy wanted to stab him, and the Kensington dudes held him down. They would make sure nobody tried to strong-arm him."
The Philly guys were basically from a white ghetto, and known as the Kensington gang bangers or KGB. They had no problem getting busy or doing a little soft extortion of their own, so it's entirely feasible that Durst was paying protection money, especially since they were "holding him down"—which in prison parlance means making sure nobody f---- with him or takes his s---. In prison, violence or protection from violence is a currency that can be traded on the open market.
Otherwise, Ferranti notes that his friend says Durst was a "nice guy," although "deaf, old, and fragile."