Illinois State Police investigate a fatal motorcycle crash on I-94 eastbound at the Lake Forest Oasis Wednesday afternoon. | Photo: North Shore Updates.

The coroner said that a 78-year-old motorcyclist who was killed after rear-ending a parked semi-truck near Lake Forest experienced a medical event just prior to the crash.

An autopsy showed George Mayer, 78, of Milford, Utah, died as a result of blunt force injuries caused by a vehicle crash, according to Lake County Coroner Dr. Howard Cooper.

The Illinois State Police said that they received a call around 1:08 p.m. Wednesday for a two-vehicle crash with injuries on Interstate 94 eastbound at milepost 18.1 in Mettawa.

A preliminary investigation shows that Mayer was traveling eastbound on a blue 2007 Honda motorcycle.

The Honda was on the ramp approaching the Lake Forest Oasis when it veered onto the right shoulder for an unknown reason and struck a blue 2019 Freightliner truck hauling a trailer.

The Honda’s front-end struck the rear of the semi-truck, which was parked.

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Mayer sustained life-threatening injuries and was pronounced dead at the scene.

The 51-year-old Hartford, Wisconsin man driving the truck was not injured. No charges or citations have been issued.

The ramp to the Lake Forest Oasis was closed at approximately 1:15 p.m. and remained closed for several hours while the traffic crash investigation took place.