Boatwright has a lengthy criminal past with several drug charges as well as an arrest for battery. Police arrested Williams two days after Onfroy's murder; he has been charged with first-degree murder, a probation violation for theft of a auto, and driving without a valid license.
Detectives said they want to speak with Allen to find out what he knows about the killing.
Though Allen is named only as a person of interest, he is also the subject of a felony warrant charging him with flakka possession, carrying a concealed firearm and a probation violation, police said.
Investigators believe Boatwright was one of two armed suspects who confronted Onfroy as he left RIVA Motorsports, an upscale motor sports dealership.
Both of the suspects fled in a dark-colored SUV.
Onfroy was taken to Broward Health North, where he was pronounced dead.
Late last month, police charged Dedrick Williams, 22, of Pompano Beach with first-degree murder in the rapper's death. The sheriff's office didn't say whether it is accusing Boatwright or the other man of killing Onfroy.
Boatwright now faces charges of first-degree murder.
In 2015, he was arrested on drug charges after being found with PVP and Cannabis, according to his rap sheet.
Detectives are actively searching for a third suspect, the Herald reported. The Broward County Sheriff's Office claims that Boatwright was one of two men who approached XXXTentacion while he was in his vehicle in an attempt to rob him.
The newspaper reports that police suspect Boatwright is one of the gunmen who actually pulled the trigger and shot XXXTentacion.