An autopsy is scheduled for a woman accused of killing the brother of Cleveland's police chief before shooting herself in the head on a Pennsylvania highway.

Dana Johnson, 36, was pronounced dead late Thursday morning at a Pittsburgh hospital, according to the Allegheny County medical examiner's office. An autopsy will be performed Friday.

Cleveland police obtained an arrest warrant for Johnson on Tuesday after officers found her boyfriend, 34-year-old William D. Williams, fatally shot at her home. He was the brother of Cleveland police Chief Calvin Williams.

Authorities who tracked Johnson suspected she was headed to Maryland, where she has relatives, said U.S. Marshal Pete Elliott of the Cleveland office.

She was alone in a vehicle in western Pennsylvania when she shot herself as troopers approached her later Tuesday morning along Interstate 376 in Brighton Township, northwest of Pittsburgh, state police said. Troopers identified her based on an alert issued for the vehicle.

A medical examiner in Ohio determined Williams died of a gunshot wound to the head, with skull and brain injuries.