A Denver man is the latest American tourist to die in the Dominican Republic this year.

Khalid Adkins died on Tuesday, the State Department confirmed to USA TODAY.

Denver's 9 News and Fox 31 report Adkins was on vacation with his daughter Mia when he fell ill in the Caribbean vacation destination.

Mia told 9 News that her father started to complain about a painful bump on his leg just before her flight home on Sunday. She said they stopped by their hotel's medical clinic, but decided against treatment unless the pain became worse.

Mia had already returned to Denver when her father's pain worsened the following day. He booked an earlier return flight but was forced to disembark due to his symptoms.

His sister-in-law Marla Strick told Fox 31 that he was dripping with sweat and vomited in the plane’s lavatory.

"They transferred him to Santo Domingo and (said) that his breathing is really bad and that his kidneys were failing," she said.

Strick noted that while her brother-in-law had undergone a kidney transplant several years earlier, he was in perfect health when he left Colorado.

Adkins' relatives said they were not even told he had died; they found out only after Mia called the hospital repeatedly Wednesday morning.

"It's been hard," she told 9News. "Not being able to get a hold of them, or them miscommunicating, or simply not knowing information."

Authorities are conducting an autopsy and investigation to determine the official cause of death, according to 9 News. (The family said they did not receive any diagnosis.)

Questions about safety have dogged the Dominican Republic since late May, when the first of several Americans died in their hotel rooms and a Delaware woman claimed she was attacked there in January.

Last week, tourism minister Francisco Javier Garcia held a press conference to dispel those concerns, stating, "The Dominican Republic is a safe country."

Garcia also said the confirmed deaths – nine including Adkins – are not out of the ordinary and that the number is actually lower than in some previous years. Garcia said that by this point in 2011 and 2015, 15 tourists had died in the Dominican Republic.

Rethinking a Dominican Republic vacation:Airlines waive change fees after tourist deaths

Dominican Republic:Latest tourist death attributed to natural causes, country officials say