XXXTentacion's murder investigation just intensified as cops have officially named a second person of interest.
The Broward County Sheriff's office is searching for 22-year-old Robert Allen who may be connected to the killing of the 20-year-old rapper over a week ago. Cops say Allen was on surveillance video at the motorcycle shop in Pompano Beach where XXX was shopping before he was gunned down in his car.
It's unclear why cops believe Allen might be connected to the murder. As we previously reported ... cops have already arrested Dedrick Williams for murder and said there were at least 2 other suspects.
We broke the story ... the case has expanded beyond the scope of the Broward County Sheriff's Dept., with the U.S. Marshals also getting involved in the case and helping nab Williams.