No, being suspicious is okay, jumping to conclusions isn’t.
I will say this. Overweight old people with heart conditions do not sleep on their backs. They also tend to use extra pillows, but not on their head.
The reason why they don’t sleep on their back is they likely have sleep apnea and stop and restart breathing throughout their sleep — if they don’t have the medical equipment to deal with it. This can lead to death.
Anybody who’s conscious of this would simply not fall asleep on their back, unless they were inebriated or drugged.
The Doctor who said he died of natural causes DID NOT SEE THE BODY. She was on the telephone.