“You don’t think there are any shady doctors out there?”
I believe I already covered that in my comment:
“I suppose you might find some shady doctor somewhere who might not worry about the provenance of an organ, but it’s not likely a shady doctor would be skilled enough to do a heart transplant.”
“Also, don’t you think there could be an underground trade of organs, taken legally and illegally? And, a victim’s body could have been kept ‘alive’ long enough for the organs to be viable, and then the body disposed of in the forest?”
It’s possible, but it doesn’t seem anywhere close to the most likely scenario. If I were a detective it would certainly be low on the totem pole of theories to investigate.
“Why remove all parts of the body that could lead to identification of the body, if it was just going to be a murder and nobody could be id’d as the killer?”
As I said in another comment, that leads me to believe the killer probably knew the victim, and so would be a suspect if the victim was identified. That’s the more common explanation for why a killer would take great lengths to hide the identity of the victim.