There was a pathologist on Fox News this am that his belief it was insecticide poisoning. Something similar to this happened to a couple vacationing in the USVI’s a few years back. The hotel there was using an illegal insecticide that you can not smell see or taste. However, because the USVI’s are a US territory the bodies were preserved, flown home and toxicology autopsies were done in the US mainland. Apparently, the people also died of pulmonary edema.
So, it might just be a case of the resorts trying to kill roaches which thrive in the tropics. Unintentional poisoning.
The other possibility is that there is some psycho that is doing this on purpose to kill people by putting it into the booze in the mini bars. This could be a worker at the hotel or someone who works in the distribution chain where the alcohol comes from. That possibility would lead to random deaths wherever the booze is shipped to.
The problem is the pathologist stated it may take weeks to get back the toxicology results.