Didn't everybody think POISON GAS seconds after we heard the news?
Surely every symptom and clue, even in the very first moments (they were sick some time earlier) indicated that?
Awful tragedy but how come it took so long to decide what happened?
Mushrooms? Salad? Bollocks.

A very good bass playing friend of mine retired to Spain, and his wife had passed out due to the carbon monoxide levels being too high in their new apartment.
He called an ambulance, and she lives still, but unfortunatly he did not survive himself. As soon as we heard the story, we looked at each other and said simply "Boiler".
It`s very hard to die of mushroom poisoning, in the UK you will die if you eat a Death Cap, or a Destroying Angel, within twelve hours, these are common fungi-avoid. The simplest rule of thumb, is avoid anything with gills, and if you are not sure about collecting them do not even start. But most just give you a bad tummy, if they are inedible.
Dreadful story though, an absolute heartbreaker.

CO poisoning is usually pretty obvious in a blood test, assuming the cadaver doesn't look to be the healthiest person in the room due to the pink colouration caused my that mode of poisoning (unlike most poisons, CO doesn't cause something to break down directly, it actually suffocates you by locking on to heme and not letting go... changing the heme from blueish purple to pink)