Carbon monoxide poisoning was the cause of death of the teenage son of former New York Yankees outfielder Brett Gardner, authorities in Costa Rica confirmed.

A toxicology report after his death found high levels of carboxyhemoglobin, an indicator of carbon monoxide in the blood, according to a statement from Randall Zúñiga, the director of the Costa Rica Judicial Investigation Agency. Miller Gardner’s test showed a saturation of 64 percent, he said, adding that anything over 50 percent was lethal.

Miller Gardner, the 14-year-old son of former New York Yankees outfielder Brett Gardner, is believed to have died as a result of carbon monoxide poisoning.

A high level of carbon monoxide was detected in 14-year-old Miller Gardner's hotel room, Costa Rican Police revealed.

The New York Yankees star’s 14-year-old son was found dead in his hotel room during the family’s vacation in Costa Rica.

After initially having disregarded it as a potential cause of death, Costa Rican officials said the teen son of former New York Yankees outfielder Brett Gardner may have died during family vacation as a result of carbon monoxide poisoning.

The death of former New York Yankees outfielder Brett Gardner's son is now being investigated as a possible carbon-monoxide poisoning, investigators said Monday. Gardner's 14-year-old son, Miller, died in March during a family trip to Costa Rica. The Gardner family announced his death in a statement released by the Yankees two days later.