An investigation has determined that the recent death of a veteran Warren firefighter was accidental. Trumbull County Coroner, Dr. Humphrey Germaniuk tells 21 News that Casey Klein's death was due to traumatic asphyxia. Klein was in an ATV accident in Vernon Township last week. A Norfolk and Southern train crew spotted Klein beneath an ATV in a ditch near Fisher Corinth Road. Klein was a member of the Warren Professional Firefighters union for 16 years and an Air Force Reservist.