Robert J. Turner, 32, died Friday at the University of Illinois Medical Center at Chicago's intensive care unit after he was transferred there last Wednesday, according to the Cook County medical examiner's office.
Turner was on a medical furlough from the Dixon Correctional Center and was being treated for a number of maladies, including cirrhosis of the liver, authorities said.
An autopsy performed Sunday determined that Turner died of necrotizing fasciitis -- more commonly called the flesh-eating bacteria -- and sepsis and his death was ruled natural, according to the medical examiner's office.
The flesh-eating disorder is a rare but severe type of infection that can destroy the muscles, skin and other underlying tissue.
Turner was 18 when he and two other men were charged with the shooting death of Derek Miles, 18.
Chicago police said Turner and the other men confronted Miles and two companions on the street and demanded money. After Miles and his companions could come up with only $15, one of victims offered to hand over valuables stored in Miles' home.
The victims and robbers went to the home in the 6300 block of South Albany Avenue, police said. While the three suspects collected stereo equipment and other items, Miles slipped away and got a gun from another part of the house.
When Miles returned and confronted the three men, police said someone fired several shots and killed Miles.
Officials from the Illinois Department of Corrections weren't immediately available for comment this morning.