Some American families are questioning a string of recent deaths of loved ones vacationing in the small island nation.

DENVER — A Denver man died recently after he became ill while on vacation in the Dominican Republic, according to the country's U.S. consulate.

Khalid Adkins' family is working to get his body back to Colorado, the consulate said.

The consulate said it's unclear exactly when or how Adkins died, but authorities are conducting an autopsy and investigation.

Family members aren't sure whether Adkin's death is connected to at least nine other American tourists' death this year in the Dominican Republic, or if it's just a coincidence.

Elijah Adkins, Khalid Adkins' brother, told 9NEWS Khalid Adkins was fine before he left.

"We just got done painting the inside of his house," Elijah Adkins said, adding that Khalid Adkins was supposed to spend the Fourth of July at a barbecue with all his brothers.

Khalid Adkins traveled to the Dominican Republic with his daughter, Mia Adkins.

"It was going to be like a Father's Day, father-daughter trip out there," she said, listing just some of the excursions from their trip.

"We went ATV-ing, went to the beach, went to caves out there ..."

Mia Adkins said she could only stay for a week since she had to return to work, but her father planned a longer trip for himself.

Just before her flight home Sunday, Mia Adkins said her father started to complain about a painful bump on his leg that looked like a bug bite. She said they stopped by a medical clinic at the hotel, but decided against treatment unless the pain became worse. Mia Adkins said her dad dropped her off the airport soon after.

"That’s the last time I saw my dad," she said.

The next day, Khalid Adkins told his family the pain was much worse. With their help, he rescheduled his flight and planned to fly home early.

But he never made the flight.

Khalid Adkins' sister-in-law, Marla Strick, got a message from Khalid Adkins on Facebook.

"He said, 'I was on the plane and shivering and I went to the bathroom to throw up, and they kicked me off the flight,'" she said.

Khalid Adkins was in the hospital. The family struggled through language barriers and a foreign medical system, and getting answers wasn't easy. They learned Khalid Adkins was having breathing issues, and that his kidneys were failing. He'd had a kidney transplant several years before, they said, but was perfectly healthy when he left Colorado.

"It's been hard," Mia Adkins said. "Not being able to get ahold of them, or them miscommunicating, or simply not knowing information."

Wednesday morning, Mia Adkins learned her father had died. Nobody called the family to tell them, she said. Instead, Mia Adkins said she learned the news after repeatedly calling the hospital. Khalid Adkins's exact diagnosis, and what treatment he received, is still a mystery.

"I just don’t understand what's going on," Strick said. "He was happy, fine. And to fall ill and die two days later? It just doesn’t make sense, and we can't get any answers."

“If he would’ve made it back he probably would’ve made it," said Elijah Adkins.

In addition to his daughter, Khalid Adkins leaves behind his son, Khalid Jr.

Tourism Minister Francisco Javier García last week said the string of deaths of American tourists on the small island south of Cuba are not a mysterious wave of fatalities, but rather a medically and statistically normal phenomenon that's been lumped together by the U.S. media, according to a report from the Associated Press.

García said five autopsies are complete and show the tourists died of natural causes, and that Dominican officials are confident the three deaths still under investigation are also from natural causes.

But many Americans have came forward saying they thought their family and friends had become victims of unexplained deaths, many of which happened after drinking alcohol.

Some have speculated it's due to adulterated alcohol or misused pesticides.

Here's a list of those who have died in the Dominican Republic this year, according to the Associated Press:

Jan. 26: Jerry Curran, 78, died at the Dreams Punta Cana resort. An autopsy report blamed pulmonary edema and other causes, García said.

April 12: Robert Bell Wallace, 67, of California died of septic shock, pneumonia and multi-organ failure.

April 19: John Corcoran, 70, died of natural causes. Corcoan's family members said he had a pre-existing heart condition. Officials haven't released further details.

May 25: Miranda Schaup-Werner of Allentown, Pennsylvania: Family members said she died after getting a drink from the minibar at the Luxury Bahia Principe Bouganville hotel. The autopsy found she died of a heart attack, according to García.

May 30: The bodies of Edward Nathaniel Holmes, 63, and Cynthia Ann Day, 49, were found in their room at the Grand Bahia Principe La Romana hotel.

June 10: Leyla Ann Cox, 53, died from a heart attack, García said. She had signs of a previous heart attack.

June 13: Joseph Allen, 55, died of a heart attack at the Centro Vacacional Terra Linda resort in Sosua.

9NEWS Medical Expert Dr. Comilla Sasson said the American deaths in the Dominican Republic have puzzled the medical community.

"Nobody really knows why, right? Nobody really knows what happened," she said. "You can't tie it to an environmental exposure, you can't say it was food poisoning, you can't say it was the alcohol that was tainted, was it trauma? Nothing really ties all this together, they’re different geographic locations."

She added:

"So is the number of deaths we've seen only because we've heard about them, and this would have been the normal number of deaths (that) could have happened any given year... Or is it more? I don’t think I know the answer about that."