Complex sentence: During Stefano Monastero regime as boss in the late 1920s, he rivaled other Pittsburgh gangs and a Chicago gang, he and his brother were eventually murdered on August 4,1929.
Split into simpler sentences: During Stefano Monastero's regime as boss in the late 1920s, he rivaled other Pittsburgh gangs and a Chicago gang. He and his brother were eventually murdered on August 4,1929.