An autopsy conducted yesterday on a Jeep worker who died after he was found unresponsive inside the Toledo North Assembly Plant showed the preliminary cause of death was a broken neck.

Michael Tiller, 50, of Lambertville, was pronounced dead about an hour after he was found by a colleague early Tuesday morning.

The coworker found Mr. Tiller on the rollers of a large machine that he operated called a battery washer, authorities said.

The autopsy showed that the preliminary cause of death was blunt neck trauma, and the case is being considered an accident.

The exact circumstances surrounding the accident are unknown because no one witnessed the fall inside the Chrysler Drive plant, said Dr. Cynthia Beisser, Lucas County deputy coroner.

A final ruling is pending toxicology tests.

Authorities said the death does not appear to be criminal or suspicious.

The longtime Jeep worker began working about 5:10 a.m. His relief arrived about 6:30 a.m. and found him unconscious and unresponsive, police said.

The U.S. Occupational Safety and Health Administration is investigating the incident. No violations have been issued.

OSHA investigators returned to the plant yesterday to gather additional information, such as why Mr. Tiller was outside the machine's control booth, according to Jule Hovi, the agency's area director.

First Published February 14, 2007, 10:40 a.m.