Authorities say 18-year-old Raheen Simmons of Camden shot Antwan Brown and Travon Kinard as they sat in a parked car in Camden on July 26.
Simmons is already held in the Atlantic County Jail on charges stemming from the Sept. 18 carjacking.
Simmons and two other men are accused of killing of 28-year-old Sunil Rattu of Old Bridge after forcing him from the Trump Taj Mahal parking garage.
Twenty-four-year-old Radha Ghetia was also shot but survived.
