DJ Khaled Fiancee's Brother Murdered In Supposed Drug Deal

DJ Khaled's fiancee's brother was murdered after an alleged drug deal gone bad ... TMZ has learned.

Cops say Nicole Tuck's younger brother, Jonathan, was shot in the face after he allegedly showed up at a Bronx apartment Sunday to buy weed. We're told the apartment was less than a mile from Tuck's home ... he allegedly got into an argument there and was shot. He was taken to a hospital where he died.