Melly, 19, who recently collaborated with Kanye West on the track "Mixed Personalities" and is best known for his song "Murder on My Mind" allegedly shot aspiring rappers Anthony Williams, 21, and Christopher Thomas Jr., 19, on October 26. Police believe that after Melly shot and killed the two victims, he and Henry damaged the Jeep Compass to make it appear as if a drive-by shooting had taken place.
Investigators said the victims were killed early in the morning of October 26 and driven in a Jeep Compass to the emergency room entrance of Memorial Hospital Miramar, which is 32 kilometres west of Fort Lauderdale.
The Sun Sentinal reports that Demons' alleged accomplice Cortlen Henry, was the driver of the Jeep.
Melly's friend Cortlen Henry, 20, was also arrested and charged with two counts of first-degree murder.
The rapper appeared in court on Thursday, where he was ordered to be held in jail without bail.
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"Those were his best friends", he said.
"A couple of months ago, I lost my two brothers by violence and now the system wants to find justice".
Both of the victims feature in a documentary about Mr Demons on his YouTube channel, where they are described as his childhood friends.
Authorities say Demons and Henry staged the crime scene to resemble a drive-by shooting after Demons allegedly shot and killed Williams and Thomas. The South Florida rapper, whose real name is Jamell Maurice Demons, turned himself in to police in Miramar. A Billboard profile previous year highlighted his "undeniable voice" that was "raw, emotive, and haunting".
The victims, Christopher Thomas Jr and Anthony Williams, were both rappers from the same Florida-based crew.