Just get the facility staff to fudge the paperwork. No need for elaborate nonsense. It isn’t like they are just going to allow any random person to come and check the corpse’s liver temp.

All they have to do is announce it, get staff to fudge the paperwork to look legit, then they embalm the body for the funeral or cremation and the evidence is gone.

There is also the possibility he is clinically dead (no brain activity but still has biological activity) but not physically dead (no biological activity whatsoever) and they are just going to have his wife conveniently decide to pull the plug. Then there is no need to fudge the numbers.