Alhambra, IL – One turkey hunter died and his son was in critical condition Saturday after a relative found them unresponsive near Alhambra in their camper, which had a portable propane heater inside.

The deceased is Galen S. Underhill, 56, of rural Collinsville.

Madison County Sheriff’s Capt. Brad Wells said the relative called 911 shortly before 6 a.m. Saturday to report finding the men unresponsive. The two men were staying in the camper on the property of an acquaintance and planned to go turkey hunting Saturday morning.

A propane bottle with a portable heater affixed to it was found inside the camper.

“We are investigating this as if it was a case of carbon monoxide poisoning,” Wells said.

Coroner Steve Nonn said, “Preliminary cause of death appears to be from carbon monoxide inhalation.”

Both men were taken to Anderson Hospital in Maryville. Underhill was pronounced dead at the hospital, while his son was flown by helicopter to a St. Louis hospital, where he remained Saturday in critical condition.

Funeral arrangements for Underhill were pending at Herbert Kassly Funeral Home in Collinsville.

Carbon monoxide is the nonirritating, odorless gas that is a by-product of burning natural gas, kerosene and other fuels, and it is the leading cause of poisoning in the United States. According to the Illinois Department of Public Health, one of the four main sources of carbon monoxide in the environment is faulty heating equipment, such as propane space heaters. In 2007, a law in Illinois went into effect that required at least one carbon monoxide alarm be installed within 15 feet of every bedroom in homes.