Authorities are looking for Robert Allen, 22-years-old, who is also wanted on a felony warrant.
XXXTentacion, whose real name was Jahseh Onfroy, was shot and killed last month outside a Fort Lauderdale motorcycle dealership.
Detectives say an SUV blocked his luxury sports car and two masked men confronted the 20-year-old rapper during what appeared to be an attempted robbery.
Dedrick Williams, 22-years-old, was arrested days after Onfroy's death in connection to the murder.
He faces murder charges but has not yet entered a plea.