Miller Gardner -- the 14-year-old son of former New York Yankees outfielder Brett Gardner -- died from carbon monoxide poisoning, Costa Rican authorities have said.

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.

When carboxyhemoglobin saturation exceeds 50%, it is considered lethal. In Gardner’s case, the test showed a saturation of 64%.