Samples extracted from three American tourists who died at a resort in the Bahamas under mysterious circumstances have been sent to a lab in the United States to expedite results and help authorities understand what happened, officials said Monday.

The police commissioner of the Bahamas, Paul Rolle, said officials also collected samples from the rooms where the tourists were staying and the surrounding property to determine whether any contaminants were present.

“We really want to know what caused this,” he said.

On Monday, Police Commissioner of the Bahamas Paul Rolle identified the victims as Michael Phillips, 68, and wife Robbie Phillips, 65, travel agents from Tennessee, and Vincent Paul Chiarella, 64, of Panama City, Florida.

Chiarella’s wife, Donnis, was airlifted to a hospital in Florida and remains in serious condition, Rolle said.

Their son Austin was with them at the resort. He was unharmed but has since told ABC News that his mother woke up ‘paralyzed’ and found her husband unresponsive.

Their bodies were found Friday morning at the Sandals Emerald Bay resort in Exuma, where the couples had been staying in two separate villas.

The samples were sent to a lab in Philadelphia, with results of the toxicology study expected in about a week, Rolle said. He noted that the Bahamas’ Department of Environmental Health and police officers are still at the resort.

When asked what he thinks might have caused the tourists’ deaths, Rolle said: “I’m not going to speculate.”

He noted that all four tourists went to a doctor the night before their bodies were discovered and they had complained of feeling ill. He said they went at different times and had eaten different things.

Steve Mulder told DailyMail.com his sister Donnis is in intensive care at a hospital in Miami and that she is covered in rashes.

Mulder said the family expects the results of Vincent’s autopsy to be released on Monday.

There is speculation that their deaths could have been caused by faulty air conditioning.

“When they got to the hotel, the air conditioner wasn’t working,” Mulder said. “They [staff] were working on it every day.”

According to USA Today, he State Department is “closely monitoring local authorities’ investigation into the cause of death,”

“We stand ready to provide all appropriate consular assistance. Out of respect for the privacy of the families, we have nothing further to add at this time.”

Meanwhile, Sandals Resorts said it would not comment further beyond its original statement, which noted that it is supporting the investigation and the families of those affected.

“Out of respect for the privacy of our guests, we cannot disclose further information at this time,” the company said.