A second teenager was charged in the string of robberies that ended in the Nov. 19 shooting death of a University of Chicago student.

Demetrius Warren, 17, of the 5800 block of South Michigan Avenue, is charged with three counts of armed robbery and one count of aggravated discharge of a firearm, Chicago Police Officer Marcel Bright said Thursday.

On Wednesday, Eric Walker, 16, was charged with first-degree murder in the case, Bright said.

Walker, of the 7700 block of South Marshfield Avenue, drove the car the teens used to commit  a series of robberies in the area, according to state attorney's office spokesman Andy Conklin.

According to Conklin, Walker remained in the car, a borrowed silver Pontiac with two red doors, while Warren and a third, unidentified male went to rob 28-year-old Abdou Cisse in front of his off-campus Hyde Park apartment.

Bright said police have not yet determined who fired the  shot that killed Cisse, a doctoral student at the university who was to have graduated next month.

Walker, who has been charged as an adult, told police he knew someone in the car had a .22-caliber gun, Conklin said. He is also charged with three counts of armed robbery and charged as a juvenile for the discharge of a weapon, Conklin said.