Oswald in the doorway: the blog of the Oswald Innocence Campaign, by Ralph Cinque

Here is something that I have long suspected. A study out of Italy concerning carbon monoxide deaths said:

"Most cases of poisoning have been caused by precarious or obsolete heating systems."

There was a much higher risk among poor immigrants. 

"Inspections revealed that immigrants for economic
reasons often live in poor houses with unsafe systems
or, in more serious cases, with extremely precarious
heating systems such as open fires in closed rooms or
in ramshackle shelters. Often poor and excluded people,
especially foreigners, are forced to rent property of low
quality, sometimes even in ruinous state, whose rents
are similar or even higher than those paid for a normal
dwelling; these “homes” (already refused by the native
inhabitants) are often the only choice that market offers
in the town."

This was Italy, but there is every good reason to think that the same applies here in the U.S. Rich people, like the Altgens, can afford to get a safe system and have it regularly inspected and maintained; hence, they have a much lower risk of accidents involving CO. 

All but the bloodied should be open to the possibility of foul play in the deaths of James and Clara Altgens.