SCHAUMBURG, Ill. (CBS) — Felony charges of first-degree murder have now been filed in a stabbing that killed 18-year-old Manny Porties in Schaumburg back in September, after the Cook County State’s Attorney’s office initially rejected such charges.

Around 3:10 p.m. Monday, Schaumburg police detectives arrested a 17-year-old male suspect in the stabbing that killed Porties on Sept. 28 in the 600 block of Sturnbridge Lane.

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Police said the State’s Attorney’s office has now approved felony charges, after they were initially denied based on lack of evidence.

“I am grateful that the continued diligence and investigative work of our detectives helped to bring justice for the Porties family,” Schaumburg police Chief Bill Wolf said in a news release.

“The Schaumburg detectives and the Cook County Assistant State’s Attorney’s collaboration on this case is an example of the system working effectively to bring justice for the Porties family and the people of Cook County,” Cook County State’s Attorney Kim Foxx said in the release. “We are incredibly grateful for the thoroughness and dedication of the Schaumburg Police Department.

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Porties, of Elgin. was killed when he showed up for a fist fight.

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 was initially just charged with unlawful use of a weapon – a misdemeanor.

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A spokesperson for Foxx’s office later said there was insufficient evidence in the case.

CBS 2 Chicago Staff