Columbia Daily Tribune – Preliminary results of an investigation into the death of Hickman High School teacher Dennis Dallman, 56, show he died of accidental carbon monoxide poisoning, the Boone County Sheriff’s Department said.

Deputies found Dallman dead in his home Wednesday morning with his car running in his garage.

An autopsy was performed yesterday. The finding is still considered preliminary pending toxicology results and other lab tests conducted by the medical examiner’s office.

Dallman’s is the fourth area death attributed to accidental carbon monoxide poisoning this year. In March two women and a 10-year-old girl died in a home on Primrose Drive after a car was left running in a closed garage.