One theory is that Poe was beaten to death when he drank to much at the bar with his friends. He then wandered off and maybe ran into some guys who stole and beaten him to death.
Another cause of death could be from carbon monoxide poisoning. When Poe died his hair tested for certain heavy metals and it showed inconclusive. He could’ve got the poisoning from his indoor lighting but since the results were inconclusive no one is for sure.
The last theory could be a lot less sinister theory and that his flu could of turn for the worse and caught Pneumonia.