ATLANTA—Rapper Young Thug co-founded a violent street gang and promoted it in his songs and on social media, prosecutors allege in a sprawling indictment that accuses him and 27 others of racketeering and a laundry list of other crimes meant to further the gang’s interests. The Atlanta-based rapper, whose given name is Jeffrey Lamar Williams,…

ATLANTA—Atlanta rapper Young Thug cofounded a violent street gang and promoted it in his songs and on social media, prosecutors allege in a sprawling indictment that accuses him and 27 others of racketeering and a laundry list of other crimes meant to further the gang’s interests. The rapper, whose given name is Jeffrey Lamar Williams,…