It could be weeks before authorities know exactly what killed a Norfolk Southern engineer this week.

Steve Warren, 56, of McDonough, was found dead about 4 feet from a parked train near Waterville Road and Raines Avenue about 2 a.m. Monday.

The train conductor told Macon police he heard a thump at the rear door of the engine after Warren said he was taking an engine off line, according to a Macon police report.

Bibb County Coroner Leon Jones said Tuesday’s autopsy results are pending toxicology testing, but Warren did suffer a severe injury in an apparent fall from the train.

Warren had been battling a cold and might have gotten dizzy, Jones said.

Investigators are trying to determine if Warren suffered another medical emergency that led to the fall.