Shark Tank star Barbara Corcoran is speaking out about her brother's death amid an FBI investigation into seemingly mysterious tourist deaths that have occurred over the past year in the Dominican Republic.

TMZ reported Wednesday that the ABC star's brother John died of a heart attack at 60 in April during an annual vacation to the Dominican Republic, with Corcoran calling into question the surrounding circumstances to the outlet months later.

The businesswoman called John her "favorite brother" among her nine siblings, and revealed he was waiting on his girlfriend's arrival at the hotel at which he was staying when he was found dead in his hotel room. Corocan did not specify the hotel at which he was staying, but told the outlet there has yet to be an official autopsy done.

John's death came amid a rash of U.S. tourist deaths in the Dominican Republic, with NBC News reporting six people being found dead under similar circumstances since June 2018 — two at the Hard Rock Hotel & Casino Punta Cana, and four at various Bahia Principe resorts. Three of these deaths have been attributed to heart attacks, while another listed pulmonary edema as a contributing factor, with respiratory failure also being noted in the death of a Maryland couple found dead in their room last month.

The FBI is investigating the deaths of three of those Americans who died at the same resort, the U.S. embassy in the Caribbean nation told NBC Tuesday.

Further toxicology results on the three U.S. tourists could take up to 30 days, the FBI noted, with the embassy saying in a statement, "We ask everyone to be patient while these investigations run their course."

A statement from Bahia Principe Resorts denied the deaths had anything to do with one another or the property, saying in a statement to NBC, "We completely disagree with the dissemination of false information issued publicly which threatens the image and reputation of the company and the integrity and rights of our employees and their families, reserving, where necessary, the right to take appropriate legal action."

Photo credit: Instagram/Barbara Cocoran