Preliminary findings blame a propane-powered Nissan forklift for the fatal carbon monoxide poisoning of Bobby Ammons, 57, in a Norton Creek Farms packing facility on 2 August.

Sixteen others, mostly emergency responders including sheriff's deputies, paramedics and firefighters, experienced signs of exposure to the colourless, odourless, tasteless gas and received treatment at a hospital.

Investigators may take weeks or months to complete their investigation, says Bill Best, senior health compliance officer in Asheville, North Carolina, with the occupational safety and health division of the state's department of labour. "The maintenance records have not been received yet."

The agricultural operation's owner acquired the heavily used forklift about one year ago, Best says. "We could not read the tag withinformation" about the year and model of the equipment.

Ammons and Melvin Lands, 43, were found unconscious in a semi-trailer being loaded with blackberries from an adjacent refrigerated room at the produce farm. Ammons died at the scene. Lands was airlifted to Greenville Memorial Hospital and discharged after three days.

A computer-aided dispatch from Macon County emergency management services indicates two firemen's detection monitors indicated emission of high levels of carbon monoxide from the forklift.