The fatal shooting occurred at about 3 p.m. Saturday in the 7300-block of South Aberdeen Street in the Englewood neighborhood on the city's South Side.
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DeShawnti Hillard, the victim's 10-year-old niece who was inside the bedroom when the shooting happened, described the incident in chilling detail.
"He put the gun to me first because I didn't want to lend him my phone. And the way he did it to me, I guess there were no bullets in it or anything. Then I went to the bathroom and when I came back, I sat down and was on my phone. And I heard Deon tell [him] that he was not playing with him. And [he] was like I'm not playing with you either and he shot him," she said.
Williams was shot in the chest and transported to a hospital, where he later died.
It's not clear whether the boy believed the gun was not loaded, but he disappeared shortly after the shooting. Police said they are in touch with his family as they continue their investigation.
Police believe the shooting was accidental and so does Williams' family. But despite their attempts to get the teenage boy who pulled the trigger to turn himself in, he has yet to do so.
"It's a tragedy. It happened. Both families are impacted," said Donald Williams, the victim's father. "I can't speak for the rest, how the other family feel. His mom and I feel the same, it was an accident and we just want him to turn himself in and get the proper help."
Williams' father has even offered to walk the boy into the police station himself as a way to guarantee his safety.
"They're looking at so much social media with threats. They're scared. He's scared," crisis responder Andrew Holmes said. "They do want to come in. But they want to come in with him safe and sound and give his accountability. And talk to the state's attorney and talk to the detectives."
Family and friends remembered Deon as a fun-loving kid who enjoyed basketball and dance. He was a Mays Elementary Academy student.