The teen who police say was dragged for a half mile on Gallivan Boulevard last week died Wednesday morning, after four days on life support, State Police and the Suffolk County District Attorney's office report.

By the end of Wednesday, the DA's office had filed murder charges against the two people accused of dragging Kemoni Miller, 18, after they robbed him of a phone - Kenneth Ford, 23, of Roxbury, and Dejon Barnes, 18, of Worcester. The two had initially been charged with unarmed robbery.

In a statement, State Police and the DA's office say:

"The investigation, led by State Police assigned to the Suffolk County Detective Unit with the assistance of Troop H detectives and Boston Police, suggests that Miller had negotiated the sale of an iPhone XS to Barnes online. On Friday night, the evidence suggests, he met with Barnes and Ford on Gallivan Boulevard. The defendants allegedly travelled to the scene in a vehicle rented by Ford’s friend. From the passenger’s seat, Barnes allegedly took the phone and closed his window on Miller’s arm as Ford accelerated at a high rate of speed.

"Miller was dragged about half a mile and suffered a life-threatening head injury when he fell from the car. He was transported to Boston Medical Center but never regained consciousness."