LOS ANGELES — As a trial approaches for the sole suspect charged in the slaying of Tupac Shakur, the rapper’s stepbrother has filed a wrongful death lawsuit stating that for “the first time in nearly 30 years, threads are starting to come together” regarding the various parties involved in the infamous murder. Maurice Shakur, known by his stage name, Mopreme, filed a complaint in Los Angeles Superior Court on Tuesday seeking damages against Duane “Keffe D” Davis and additional unnamed defendants accused of participating in the rap legend’s killing. Tupac Shakur was shot in Las Vegas on Sept. 7, 1996. As he rode past the MGM Grand Hotel and Caesars Palace in a BMW, a white Cadillac pulled up alongside and a gunman opened fire, striking the hip-hop icon four times. Over the course of three decades, multiple law enforcement agencies tried to crack the case as conspiracy theories involving complex gang and music-related rivalries swirled.…