Joseph Allen of Avenel, New Jersey, is confirmed to be the ninth American tourist to die at a Dominican Republic resort under mysterious circumstances while visiting the Caribbean country.

The 55-year-old was found dead in his room on Thursday (June 13) at the Terra Linda Resort in Sousa. The resort is a different one from where other Americans have recently passed away.

According to his family, he was celebrating a friend’s birthday. A toxicology report hasn’t yet been performed because the island’s toxicology machines have reportedly been down.

Jamie Reed, Allen’s sister, told ABC News that friends who were on holiday with her brother said he complained of feeling hot in the pool and went to take a shower.

By evening he said he still wasn't feeling right. The next day, after Allen didn't show up for breakfast and didn't answer his door, hotel staff performed a wellness check and discovered him dead on the floor of his room. Allen was reportedly healthy prior to the DR visit and would visit the country multiple times a year.

Last week, the FBI joined in to assist in investigating the deaths in the Dominican Republic and their causes. According to the U.S. Embassy in Santo Domingo, officials in the Dominican Republic asked the FBI to assist in conducting toxicology analysis on the bodies and the resorts run by the Bahia Principe Hotels & Resorts.

Allen becomes just the latest tourist in the Dominican Republic to die under suspicious circumstances since 2018. Just three days earlier, 53-year-old Leyla Cox also died in her hotel room at the Excellence Resorts in Punta Cana. The hotel gave the cause of death as a heart attack, reportedly citing a forensics report.

Tourist groups are also reporting concerns after five members of an Oklahoma high school group became violently ill after eating at a Japanese restaurant last week and more than 50 Jimmy Buffet fans were sickened while on an annual trip in April of this year.

Health officials say heart attacks are the most common cause of death for Americans on vacation. Some of the relatives of those who have mysteriously died however have demanded autopsies be performed on their loved ones.

The family of 63-year-old Edward Nathaniel Holmes 49-year-old and Cynthia Ann Day want independent autopsies performed on the couple, who Dominican authorities say died of respiratory failure and pulmonary edema.

The couple died just days after Miranda Schaupp-Werner, 41, was found dead at the Luxury Bahia Principe Bouganville hotel at the same resort. Schaupp-Werner’s cause of death was the same as Holmes and Day.

An official at the U.S. Department of State said they are "actively monitoring" the investigations into the deaths of the Americans in the Dominican Republic. "At this point, we are not aware of any connection between these incidents," the official told ABC News in a statement.