Three American tourists who were found dead at a resort in Sandals in the Bahamas in May have died of carbon monoxide poisoning, police said Tuesday.

In a statement, the Royal Bahamas Police Force said the three victims, identified as Michael Phillips, 68, and Robbie Phillips, 65, of Tennessee; and Vincent Chiarella, 64, of Florida, had died of asphyxiation from carbon monoxide poisoning.

They said the investigation into the deadly incident is still ongoing.

The three Americans were found dead on May 6 at the Sandals Emerald Bay Resort in Great Exuma.

Chiarella’s wife, Donnis, 65, was flown to a Florida hospital in serious condition. The hospital, HCA Florida Kendall in Miami, later said her health had been upgraded to “fair condition.” NBC Miami reported† Her current condition was not immediately known.

The couples stayed in separate villas on the resort.

Police previously said an initial investigation revealed that one of the couples had complained of illness the night before they were found. They had visited a medical facility, were treated and then returned to the villa, police said.

It was not clear whether the villas were equipped with carbon monoxide detectors or whether they were working.

Sandals did not immediately respond to a nightly request for comment from NBC News.

The resort giant said in May that Bahamian authorities had concluded the incident was “isolated” and “in no way related to the resort’s air-conditioning system, food and beverage services, landscaping services, or malicious intent”.

It said carbon monoxide detectors had “now been installed” in all guest rooms at Sandals Emerald Bay, despite being “not required in a Caribbean destination where we operate”, adding that detectors would be installed in all guest rooms in its portfolio. .

The dead have cast a cloud over the resort hotel since the incident unfolded. The location is billed as an adults-only enclave with 11 restaurants and a golf course overlooking a secluded stretch of beach.