FORT LAUDERDALE, Fla. -- A second person has been arrested in the June shooting death of emerging rap star XXXTentacion, authorities in Florida announced Wednesday.

Michael Boatwright, 22, is facing first-degree murder charges in the killing, the Broward Sheriff's Office said in a news release.

Boatwright was initially arrested last week on an unrelated drug charge, investigators said. Jail records didn't list an attorney for him.

Also charged in the killing outside a Deerfield Beach motorcycle shop is Dedrick Williams, 22. His lawyer has said he will plead not guilty.

Authorities say robbery was the motive in the killing of the 20-year-old XXXTentacion, whose real name was Jahseh Onfroy.

Detectives still want to talk with a third man, 22-year-old Robert Allen, who is described as a "person of interest" in the case and may know something about the killing. Allen is also wanted in Broward County on a felony warrant for violation of probation for possession of the drug flakka and carrying a concealed firearm, according to the sheriff's office.

XXXTentacion, who sported dreadlocks and facial tattoos, and who pronounced his name "Ex ex ex ten-ta-see-YAWN," was a platinum-selling rising star who tackled issues including prejudice and depression in his songs. He also drew criticism over bad behaviour and multiple arrests, including charges that he severely beat and abused his girlfriend.

Thousands of fans turned out last month for a music-filled memorial service held at a 20,000-seat arena that is home to the Florida Panthers hockey team.