Police are investigating whether a medical condition was to blame for a single car crash on I-94 Saturday evening that killed a 57-year-old Willis woman.

Michelle Adriann Stoj was pronounced dead at the scene of the 9:30 p.m. crash on westbound I-94 in Lima Township, said Michigan State Police Sgt. Chris Pascoe of the Ypsilanti post.

Pascoe said Stoj's vehicle left the roadway near Dancer Road and went into a ditch. She was the only occupant.

Pascoe said alcohol does not appear to be a factor, and police are investigating whether a medical condition may have caused Stoj to lose control of the vehicle. Police are awaiting autopsy results.

The expressway was closed at Baker Road for several hours while troopers investigated.

Pascoe asked anyone who witnessed the crash to call Michigan State Police at 734-482-1211.