Julius Campbell was last seen at Gage Park High School where he was a freshman.
Campbell's body was found on April 12. An autopsy found that he suffered multiple stab wounds and his death was ruled a homicide.
Campbell's mother says he was a bright, hardworking boy who befriended everyone. She says the weeks of uncertainty were hard and confusing.
"My emotions are everywhere," Christina Campbell said. "I'm trying to be strong for my other children but I say to myself who's going to be strong for me?"
Chicago police have not made any arrests in the case.