Authorities in the Dominican Republic are investigating the deaths of three U.S. citizens at a resort in the city of La Romana at the end of May. All three had checked into the Bahia Principe Hotel resort on May 25, according to CNN.

It remains unclear whether the deaths of a Pennsylvania woman and a Maryland couple are connected. U.S. officials said they are actively monitoring the investigations.

Miranda Schaup-Werner, 41, who was celebrating her 10th wedding anniversary, died the day she checked into the hotel. Family spokesman Jay McDonald said Schaup-Werner had a drink at the hotel bar shortly before becoming ill. Dominican officials told the family that the cause of death was “pulmonary edema and respiratory failure” — the same cause attributed to the Maryland couple.

Dominican officials declined to confirm those findings to The Washington Post. They said toxicology tests were still pending.

McDonald said initially that they understood that local authorities refused to run toxicology tests, but were later moved to run them.

The family declined to comment further.

The Maryland couple — Nathaniel Edward Holmes, 63, of Temple Hills, and Cynthia Ann Day, 49, of Upper Marlboro — were found dead in their hotel room May 30 with prescription bottles of oxycodone in 5-milligram doses nearby. The pills are used for high blood pressure.

An autopsy showed that both died when their lungs filled with fluid, leading to respiratory failure, according to a news release from the Dominican Republic’s National Police. The pill bottles remain a subject of inquiry.

There were no signs of violence, according to Dominican officials.

The couple posted photos of themselves on Facebook enjoying time on the beach, wading in the turquoise blue waters of the Caribbean, riding all-terrain vehicles and cruising on a boat. On May 26, Holmes posted: “Can somebody please loan me $250,000 bcuz I don’t want to come home!!!!!”

More than 2 million North American tourists flock to the Dominican Republic every year. But after an attack on a Delaware woman inside her resort near Punta Cana in mid-April, the State Department alerted travelers to exercise “increased caution in the Dominican Republic due to crime."

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