Two of the three suspects accused in the Amadou Cisse murder case pleaded not guilty to all charges Friday, authorities have said.

Eric Walker, 16, and Demetrius Warren, 17, both pleaded not guilty to charges. A third suspect, Benjamin Williams, 21, has not entered a plea.

One of the three suspects allegedly shot Cisse, a U of C chemistry student, in the chest during a robbery attempt at 1:30 am on the 6100 block of South Ellis Avenue, according to Andy Conklin of the state attorney’s office.

Williams, who was arrested in mid-December, faces charges of first-degree murder, aggravated discharge of a firearm, and armed robbery, Conklin said. Prosecutors allege that Williams served as a lookout during the robberies, according to the Sun Times.

Walker has been charged with first-degree murder, attempted armed robbery, and armed robbery.

Warren was arrested soon after Walker and is accused of armed robbery, discharge of a firearm, and attempted armed robbery, according to a Sun Times report. Warren’s lawyer claims that his confession was coerced, according to a Tribune report. In the same report, Chicago Police say they followed proper procedures.

All three suspects will appear in court on January 31.

Prosecutors allege that Walker, Warren, and Williams rented a silver Pontiac from a neighbor and then drove to the 6000 block of South Woodlawn Avenue, where they attempted a series of robberies, culminating in Cisse’s murder, throughout the neighborhood. Since the murder, police have made public the previously unreported robbery of a 27-year-old male on the 5300 block of South Greenwood Avenue that night