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.

Officials in Costa Rica confirmed Wednesday that the official cause of death for 14-year-old Miller Gardner was carbon monoxide poisoning.

Brett Gardner's son Miller's cause of death has been confirmed by local authorities nearly two weeks after his death. Miller was in Costa Rica with family when he died on the morning of Friday, March 21.

Miller Gardner, the 14-year-old son of the retired Yankees player Brett Gardner, died from carbon monoxide poisoning while on vacation in Costa Rica. Here’s why the gas is so dangerous.

Miller Gardner, the teenage son of former New York Yankees outfielder Brett Gardner, died of carbon monoxide poisoning, authorities in Costa Rica said Wednesday night.

Costa Rica authorities confirmed that carbon monoxide poisoning was the cause of death of Miller Gardner, the 14-year-old son of former New York Yankees outfielder Brett Gardner.

The death of Miller Gardner, the 14-year-old son of former New York Yankees outfielder Brett Gardner, was due to carbon monoxide inhalation, the Judicial Investigation Agency (OIJ) of Costa Rica said Wednesday.

Costa Rican authorities released the toxicology report on the death of former Yankees star Brett Gardner's 14-year-old son Miller.

A blood test for carbon monoxide showed a saturation level of 64% in Gardner’s body, Costa Rican officials said. Concentrations above 50% are considered lethal.