CHICAGO (CBS) — An 18-year-old man was charged Monday with killing a 23-year-old man found shot in a car early Saturday in south suburban Chicago Heights.

At 4:16 a.m., officers found Michael Overall sitting in the driver’s seat of a blue Chevrolet Impala with a gunshot wound to the head in the 1800 block of Chicago Road in Chicago Heights, according to Chicago Heights police and the Cook County medical examiner’s office.

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Overall was initially taken to St. James Hospital in Chicago Heights, then was airlifted to Christ Medical Center in Oak Lawn, where he was pronounced dead at 5:26 p.m. Saturday, authorities said. The medical examiner’s office listed Overall’s home address in University Park, but police said he was a Steger resident.

His death was ruled a homicide, according to the medical examiner’s office.

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The Illinois State Police crime scene services were contacted to process the scene.

Trevor Keith (Credit: Cook County Sheriff)

On Monday, Trevor Keith, of Park Forest, was charged with first-degree murder, police said in a statement. Keith will appear in bond court Tuesday at the Markham Court House.

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(Source: Sun-Times Media Wire © Chicago Sun-Times 2017. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)