They didn't find carbon monoxide in the air, but that doesn't mean it wasn't there at the time.
I posted this earlier in regards to CO not being detected:
1. **Source Stops Producing CO**: If the carbon monoxide came from something like a malfunctioning heater, car exhaust, or a small fire that burned out, the source might stop emitting CO before the fire department gets there. Without an ongoing leak, the gas levels could drop.
2. **Ventilation**: CO is slightly lighter than air and can disperse through open windows, doors, or natural airflow. If someone opens a door or window after the person dies—say, a neighbor or family member checking in—the gas could clear out before testing happens.
3. **Delayed Discovery**: If the death isn’t discovered immediately, hours or even days could pass. By then, CO might have dissipated naturally, especially in a drafty or unsealed space.
CO poisoning leaves clues in the body—like cherry-red skin from carboxyhemoglobin in the blood—which a medical examiner could spot during an autopsy. So, while the fire department might not find gas, other evidence could still point to CO as the cause. It’s rare for it to vanish without a trace, but the gas itself can absolutely be gone by the time they arrive if conditions allow it to dissipate.