An 18-year-old man charged Monday with killing a 23-year-old man found shot in a car last weekend in south suburban Chicago Heights has been denied bond.

At 4:16 a.m. Saturday, 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.

Overall was taken to St. James Hospital in Chicago Heights before being airlifted to Christ Medical Center in Oak Lawn, where he was pronounced dead at 5:26 p.m., 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.

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

On Monday, Trevor Keith, of Park Forest, was charged with first-degree murder, police said in a statement.

Keith was denied bond at a court appearance Tuesday at the Markham Courthouse, according to Cook County sheriff’s office records. He was expected to return to court Dec. 6.