CO poisoning leaves a telltale bright red skin coloration in human victims. CO prevents oxygen release from hemoglobin, making venous blood near the skin as red

CO poisoning leaves a telltale bright red skin coloration in human victims. CO prevents oxygen release from hemoglobin, making venous blood near the skin as red as arterial (oxygenated) blood. I think responders would have seen this if CO was the toxic agent. It's puzzling - as you pointed out, CO2 poisoning causes extreme distress. You'd think victims would have shown evidence of that. Maybe as another poster described, asphyxiation occurred not due to CO2 poisoning, but to oxygen deprivation through displacement of air by CO2. Oxygen deficit asphyxiation is very fast (seconds) and asymptomatic. It will be interesting to see what they finally determine CoD to have been.