CHICAGO (CBS) — Protesters showed up outside Cook County State’s Attorney Kim Foxx’s office downtown Tuesday, angry over the stabbing death of a 18-year-old in Schaumburg for which felony charges were rejected.

Manny Porties of Elgin was killed when he showed up for a fist fight in the 600 block of Sturnbridge Lane in Schaumburg on Sept. 27, but the other person involved had a knife.

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On video, it appears the 17-year-old is punching the unarmed Porties, but he was actually stabbing Porties with each jab – using the hidden knife. Porties was stabbed in the heart, and died.

Porties’ family said they were stunned when prosecutors said they were not filing murder charges, arguing the teen was acting in self-defense. The teen is charged with unlawful use of a weapon – a misdemeanor.

“Kim Foxx, you need to step up!” Porties’ grandfather, Jackie Smith, said outside the George Dunne Cook County Office Building, 69 W. Washington St.

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“My grandson – he was 18 years old. His name was Manuel Porties – stabbed to death in a fist fight,” Smith said in an interview with CBS 2. “And Kim Foxx is sweeping it under the rug. We need justice.”

A spokesperson for Foxx’s office now says there was insufficient evidence in the case.

A separate decision in which no charges have been filed at all in a shootout in the North Austin neighborhood that left one person dead has infuriated Mayor Lori Lightfoot.

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A “mortified” Foxx on Tuesday stood by her office’s decision to reject charges in the West Side case, and criticized Mayor Lightfoot for making statements that “were not factually accurate” about the case, as the mayor is now calling for a federal investigation of the shooting.

CBS 2 Chicago Staff