"We can officially confirm that all three of the victims died as a result of asphyxiation due to carbon monoxide poisoning," the Royal Bahamas Police Force said in a statement to news outlets. "This matter remains under active investigation."

The source of the carbon monoxide was not clear.

Michael Phillips, 68; Robbie Phillips, 65;  and Vincent Chiarella, 64; were found unresponsive at Sandals Emerald Bay in Great Exuma on May 6. Chiarella's wife, Donnis, was hospitalized in critical condition and was reportedly discharged from a Miami-area hospital after several weeks. Her current health condition is not currently known.

"Despite initial speculation, Bahamian authorities have concluded that the cause was an isolated incident in one standalone structure that housed two individual guest rooms and was in no way linked to the resort's air conditioning system, food, and beverage service, landscaping services, or foul play," the Sandals resort said in a statement to news outlets in May.

Sandals, an exclusive resort, added that detectors for carbon monoxide—an odorless gas—have been installed in "all guest rooms at Sandals Emerald Bay and although not mandated in any Caribbean destination where we operate, detectors will be installed in all guest rooms throughout the portfolio."