Murdered broker to the stars Linda Stein had made sets of keys for several friends and co-workers, including her former aide Raul Diaz Bernal. Police are hoping to speak to all of them as they investigate who might have accessed her apartment and bludgeoned Stein to death. They interviewed Bernal, 49, last night. He was fired by Stein a few months ago from the brokerage firm Prudential Douglas Elliman, reports the Post, after a fight over a commission. Her friends, who used to call Bernal "The Cuban," say he was the only one of her close colleagues who didn't call with condolences after her death. Cops also interviewed her 62-year-old former Italian lover, Francisco Arena, says the Daily News. They're next hoping to track down Stein's high-end pot dealers (she used the drug to help combat the pain from her bouts with cancer), who friends say regularly accessed the apartment. Since surveillance videos have turned up no leads yet, police hope these interviews will shed new light on the gruesome case.