The Burlington County Prosecutor's Office said Terrance Matthews, 23, is responsible for the shooting death of a man on February 18.
Investigators say the victim, 21-year-old Davell Williamson, was inside a vehicle with another man on Millbrook Lane in Willingboro around 1 a.m. when Matthews approached and opened fire.
Williamson was pronounced dead at the hospital. The other man in the car was hit in the arm but survived.
Matthews has been charged with first-degree murder and related offenses.
Earlier this week, investigators charged Matthews with the murders of 68-year-old Jennifer Vassell and 9-year-old Ishon Mathlin Jr. on Wednesday evening.
Police were alerted to the killings on Thursday morning when a woman, Matthews' ex-girlfriend, entered the Wawa store on Springside Road in Westampton Township asking for help.
Investigators say Matthews and his ex-girlfriend had entered the store, and that's when the woman told a Wawa employee that Matthews had killed her family.
Matthews then fled the store.
Officers responded to a home in the 100 block of Eastbrook Lane and found Vassell and Mathlin dead. Both were stabbed multiple times, and Ishon appears to have been drowned in a bathtub.
Vassell was the grandmother of Matthews' ex-girlfriend, who also lives in the Eastbrook Lane home, and Ishon Mathlin was her brother.
Authorities say the murders occurred while the ex-girlfriend was at work on Wednesday. When she arrived home after work, Matthews was at the home and allegedly held her against her will through the night.
According to authorities, the motive for the killings appears to stem from an argument Matthews had with the ex-girlfriend during a telephone call earlier in the day on Wednesday.
Matthews led police on a high-speed chase on Thursday afternoon, during which he was broadcasting live on Facebook. He was apprehended after crashing his car into a pole.
He is charged with two counts of murder in that case.