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.

The former New York Yankees outfielder's 14-year-old son died last month during a family vacation in Costa Rica.

The 14-year-old son of former New York Yankees outfielder Brett Gardner died from carbon monoxide poisoning while visiting Costa Rica, local authorities have confirmed .

Miller Gardner, son of former New York Yankees outfielder Brett Gardner, died from carbon monoxide poisoning, according to Costa Rica officials.

A forensic pathologist explained to Us Weekly why the late Miller Gardner may have experienced a stronger reaction to carbon monoxide than his family

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. Miller Gardner, 14, died March 21 while the family was vacationing in Costa Rica and the cause of his sudden death was unknown before local officials conducted testing and found carboxyhemoglobin to be the cause.

The poison gas that killed Miller Gardner is especially dangerous to children and teens because they can breathe it in faster and absorb it much more quickly.

Miller Gardner, the 14-year-old son of former New York Yankees outfielder Brett Gardner, was confirmed this week to have died by carbon monoxide poisoning while vacationing in Costa Rica.