CHICAGO (CBS) — Four days after the murder of a 6-year-old South Side girl, the person police were questioning about the crime is no longer in custody.

As CBS 2’s Susanna Song reports, the release comes amid growing concern by parents for their children’s safety.

Police released the 19-year-old man Tuesday night, because the Cook County State’s Attorney’s office wanted more evidence against him to prosecute him. He was first taken into custody Monday in connection with the death of Arianna Gibson, 6.

Arianna would have started the 1st grade this week at Libby Elementary School, 5300 S. Loomis Blvd.

But over the weekend, someone opened fire through the window at her grandmother’s home in the 7400 block of South Sangamon Street.

Arianna was sleeping on the couch when she was shot and killed around 6 a.m. Sunday. Two teenagers – a 17-year-old cousin of Arianna’s and a 17-year-old family friend – were also shot, but survived.

Police Supt. Garry McCarthy addressed the incident on Tuesday night.

“Every time a crime does occur, there’s something that we didn’t do that we could have done,” McCarthy said. “That’s why I take it so personally.”

Speaking at a town hall meeting in the East Garfield Park neighborhood Tuesday night, McCarthy said he takes responsibility for every shooting.

“We’ve got to change what’s happening here on a number of different levels,” he said.

Last week, Darius Brown, 13, was playing basketball in Metcalfe Park, at 42nd and State streets, when a bullet from a drive by hit him. His family is now preparing to bury him.

At the town hall meeting, parents voiced their concerns. One mother told CBS 2’s Kristyn Hartman she even worries when her teenage son is simply playing outside.

“I try to persuade him to be in the yard, because anything can happen, and we don’t see the police like we should,” said West Side resident Sharee Washington.

McCarthy emphasized while there are a number of things police need to work on, he also needs the community’s help in providing leads for shootings and murders.

As for the case regarding Arianna Gibson, police say the investigation remains ongoing and detectives are working the case.

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