Violent Gang, or Rap Label? Prosecutors Say Young Thug’s YSL Is Both.

The case has deeply shaken the pop culture universe, especially in Atlanta, Mr. Williams’s hometown, which can stake a claim as the hip-hop capital of the world. Fans, fellow artists, record executives and influential figures including Stacey Abrams, who was the Democratic nominee for governor last year, have sounded notes of concern, even outrage.

Some have accused the prosecutor, Fani T. Willis — the aggressive district attorney for Fulton County, a Black Democrat who is best known for pursuing the criminal investigation into postelection meddling in Georgia by former President Donald J. Trump — of applying a “gang stereotype” to Atlanta’s rap community, and putting Black art on trial.

The case has prompted an outcry, given how artists from the poorest parts of Atlanta have shaped global popular music. Young Thug’s nickname and YSL’s slang term of choice — slime — has gone international, its “wipe your nose” hand gesture a popular N.F.L. celebration.

But the recent admissions in court point to a parallel reality: In Atlanta, law enforcement officials say, it has become increasingly difficult to discern the difference between some rap crews and street gangs, and to disentangle where exactly the credibility-obsessed art form overlaps with criminality.

Ms. Willis contends that Atlanta is suffering from a plague of gang violence, estimating — with a hazy explanation for the figures — that up to 80 percent of violent crimes in the area are committed by gang members. She says that an eight-year war between YSL and a rival gang known as YFN, headed by another major-label rap artist, has accounted for more than 50 incidents.

But in a city with a well-established path from the hardest streets to a world of fame, fortune and major awards shows — often via songs that chronicle, and some argue glorify, an outlaw life of drugs and guns — the nature of gang culture is also mutating, according to the authorities, with social media and music increasingly important to establishing dominance and influence.