Miller Gardner, the 14-year-old son of Yankees legend Brett Gardner, died from carbon monoxide inhalation, a toxicology report confirmed Wednesday night per the New York Post. His tragic death occurred on March 21 while the family was vacationing in Costa Rica. Just two days earlier, Costa Rican authorities disclosed that the hotel room where the Gardners were staying had dangerously high levels of the toxic gas. Several members of the family had reportedly fallen ill before Miller’s sudden passing.

Officials with Costa Rica’s Judicial Investigation Agency have confirmed that Miller Gardner died from carbon monoxide poisoning at the Arenas Del Mar Beachfront & Rainforest Resort — despite the resort initially denying reports that the invisible but deadly gas was to blame.

“The toxicology results are in, and the carboxyhemoglobin test found a saturation of 64%. Concentrations above 50% are already lethal,” Randall Zuniga, agency director, said April 2 per CRHOY.

On Monday, a Costa Rican official revealed that the family’s hotel room — situated next to a mechanical room at the resort — was found to contain “high levels of carbon monoxide.”

“It’s also important to note that next to [the family’s] room there is a specialized machine room, from which it is believed some form of contamination may have reached the guest rooms, potentially causing the incident,” Zuniga said.

Zuniga reported that testing revealed carbon monoxide levels in the family’s hotel room reached as high as “600 parts per million.”

However, the Arenas Del Mar Beachfront & Rainforest Resort disputed the official’s findings in a statement to The Post, claiming that the elevated levels of the toxic gas were detected in the mechanical room — not in the guest rooms themselves.

“The levels in the hotel room were non-existent and non-lethal. There was an error in this initial reporting,” the resort claimed earlier.

Early speculation pointed to asphyxiation in Miller’s sleep, possibly caused by choking on vomit due to suspected food poisoning. However, that theory was dismissed after authorities confirmed the 14-year-old’s windpipe showed no signs of blockage.