When Jam Master Jay, the D.J. for the pioneering rap group Run-DMC, was killed in his studio in Queens nearly 20 years ago, it struck the hip-hop world with the force of a tragedy.
Shrines to Jay, whose real name was Jason Mizell, popped up in barbershops and on street corners. People wanted to know who could have gunned down a peaceful, old-school D.J. whose group rapped mostly about sneakers, girls and basketball.
Over the next two decades, Mr. Mizell’s murder achieved a mythic status as one of the rap world’s coldest cases. There were plenty of leads, but none of them resulted in charges — until now.