Brett Gardner's 14-year-old son, Miller, tragically died from carbon monoxide poisoning.
Costa Rican officials confirmed the cause of death after they said toxicology results showed the teen had a carboxyhemoglobin saturation of 64 percent ... well above the 50 percent threshold that's considered lethal.
Costa Rica's director of the Judicial Investigation Agency, Randall Zúñiga, stated the young Gardner likely came into contact with the gas through a machine room that was situated next to where the Gardners were staying while on vacation.